# What, exactly, kills you when you leap off of a high bridge into water? **URL:** \ **Category:** Factual Questions\ **Created:** [July 3, 2011, 2:41am UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677 "2011-07-03T02:41:14Z")\ **Posts on this page:** 17\ **Page:** 3
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [July 5, 2011, 5:09pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/41 "2011-07-05T17:09:12Z")
Is there then a general rough estimation of what maximum height the average person could drop from and still, given a proper entry, survive? ---
**Author:** ![Thrasymachus](https://avatars.discourse-cdn.com/v4/letter/t/ce73a5/32.png) [@Thrasymachus](https://boards.straightdope.com/u/Thrasymachus)\ **Post date:** [July 5, 2011, 5:14pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/42 "2011-07-05T17:14:07Z")
> [@Mississippienne](#): > > I read a Reader’s Digest article years ago about a man who lept off a bridge (The Golden Gate?) trying to rescue a suicidal jumper. Worst. Rescue. Ever. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [July 5, 2011, 5:28pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/43 "2011-07-05T17:28:36Z")
> [@lieu](#): > > Is there then a general rough estimation of what maximum height the average person could drop from and still, given a proper entry, survive? The definitions involved are pretty fuzzy. For example, what do you mean by “survive?” There are incidents which might consistenly render a jumper quadraplegic, or put them in a persistent vegetative state - but they will have survived in that their heart is still beating and they still draw breath. And of course random factors such as orientation, bone strength, and muscle tone/tension will affect outcome so that survival in any given jump is not guaranteed. You’d have to treat it like a test of toxins, for which the [LD[sub]50[/sub]](http://en.wikipedia.org/wiki/LD50) is calculated. In any event, [Google may have the answer you seek.](http://www.google.com/search?hl=en&source=hp&biw=996&bih=796&q=highest+fall+into+water&oq=highest+fall+into+water&aq=f&aqi=g2g-b1&aql=undefined&gs_sm=e&gs_upl=1265l3218l0l23l12l0l1l1l0l203l1405l3.7.1l11) ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [July 5, 2011, 6:01pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/44 "2011-07-05T18:01:59Z")
I have a dumb question: The Coronado Bridge in San Diego has a 200 foot clearance to allow ships to pass underneath it. [San Diego–Coronado Bridge - Wikipedia](http://en.wikipedia.org/wiki/Coronado_Bridge) A coworker told me this “fact”: A lot of suicide jumpers die not by impact, but by becoming “stuck” in the mud bottom of the bay, and drowning. “A lot” is not defined. I don’t know the depth of the bay under the bridge, but since US Navy “L” type “gator frieghters” ( [USS Makin Island (LHD-8) - Wikipedia](http://en.wikipedia.org/wiki/USS_Makin_Island_(LHD-8)) ) pass under it, there must be a minimum of 30 feet. Is my coworkers tale BS? ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [July 5, 2011, 6:31pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/45 "2011-07-05T18:31:17Z")
> [@mlees](#): > > The Coronado Bridge in San Diego has a 200 foot clearance to allow ships to pass underneath it. [San Diego–Coronado Bridge - Wikipedia](http://en.wikipedia.org/wiki/Coronado_Bridge) > > A coworker told me this “fact”: > > A lot of suicide jumpers die not by impact, but by becoming “stuck” in the mud bottom of the bay, and drowning. “A lot” is not defined. > > I don’t know the depth of the bay under the bridge, but since US Navy “L” type “gator frieghters” ( [USS Makin Island (LHD-8) - Wikipedia](http://en.wikipedia.org/wiki/USS_Makin_Island_(LHD-8)) ) pass under it, there must be a minimum of 30 feet. > > Is my coworkers tale BS? Whereas: -20 g’s will take you from terminal freefall velocity to zero in just 24 feet of distance (see my earlier post); -a 200-foot freefall will result in an impact velocity of just 80 MPH; -impact with water from a great height produces (at least initially) decelerations in the hundreds of g’s; I’ll dare to say that Coronado Bridge jumpers are not getting stuck in the submarine mud under 30 feet of water. I don’t know much about San Diego Bay, but it’s possible they dredge to maintain the shipping channel there. If that’s true, then it’s also possible the water is much more shallow on either side of the dredged channel. That said, even if a jumper were to get stuck in such mud, that would only happen after they were killed (or at least rendered insensate) by the inital impact with the surface of the water. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [July 5, 2011, 6:37pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/46 "2011-07-05T18:37:58Z")
[Article here](http://www.voiceofsandiego.org/news/article_a1092d62-60dd-510e-9d94-4af1dc8a93f0.html) about suicides at the Coronado Bridge. Some are killed by the impact, some drown because they are unable to swim (or are unconscious) due to injuries sustained in the impact, but there is no mention of anyone actually getting stuck in submarine mud and drowning as a result. ---
**Author:** ![Crazyhorse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crazyhorse/32/31_2.png) [@Crazyhorse](https://boards.straightdope.com/u/Crazyhorse)\ **Post date:** [July 5, 2011, 6:46pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/47 "2011-07-05T18:46:11Z")
The Acapulco cliff divers mentioned upthread are said to land in about 12’ deep water after a 125+ foot dive. In addition to coping with the sudden deceleration they are able to curve themselves into an upward trajectory in that short amount of space to decelerate. With 30’ to decelerate it can’t be very likely jumpers are hitting the bottom so hard they get stuck and drown from that alone. It sounds like they get killed or knocked unconscious on impact and then sink in to the mud with no air left in their lungs to remain floating. ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [July 5, 2011, 6:55pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/48 "2011-07-05T18:55:16Z")
Ok. Thanks, everybody. I guess I got fooled with another “this ain’t no shit” story. ---
**Author:** ![Scubaqueen](https://avatars.discourse-cdn.com/v4/letter/s/c0e974/32.png) [@Scubaqueen](https://boards.straightdope.com/u/Scubaqueen)\ **Post date:** [July 5, 2011, 7:14pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/49 "2011-07-05T19:14:16Z")
> [@fiddlesticks](#): > > The Mythbusters segment called the “myth” that you can’t stay afloat in bubbly water busted. Adam was able to stay afloat and attempt to swim through the bubbles they created, but he got very tired very quickly because of the turbulence. He was basically swimming in place while doing the crawl forward as fast as he could. That isn’t to say the situation wasn’t dangerous, but they seemed to think the turbulence was what made bubbly water dangerous, and not a lack of expected buoyancy. > > _Scubaqueen’s_ story (yuck!) seems to suggest maybe they didn’t go far enough in the test though. my bad. i should have added in my post that it wasn’t \*\*\*water \*\*\*the poor guy went into. more sewage sludge than water, very thick and viscous. ---
**Author:** ![Enderw24](https://avatars.discourse-cdn.com/v4/letter/e/ba9def/32.png) [@Enderw24](https://boards.straightdope.com/u/Enderw24)\ **Post date:** [July 5, 2011, 7:28pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/50 "2011-07-05T19:28:51Z")
> [@Susanann](#): > > What about the dive off the dam made by Dr Richard Kimble in\*\* The Fugitive\*\* and the dives in\*\* Butch Cassidy\*\* when Butch and Sundance jumped off the cliff into that little river? Are those 3 dives not possible? They used a dummy on that scene in The Fugitive. And they lost the dummy after the dive. ---
**Author:** ![levdrakon](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@levdrakon](https://boards.straightdope.com/u/levdrakon)\ **Post date:** [July 5, 2011, 7:45pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/51 "2011-07-05T19:45:18Z")
> [@fiddlesticks](#): > > The Mythbusters segment called the “myth” that you can’t stay afloat in bubbly water busted. Adam was able to stay afloat and attempt to swim through the bubbles they created, but he got very tired very quickly because of the turbulence. He was basically swimming in place while doing the crawl forward as fast as he could. That isn’t to say the situation wasn’t dangerous, but they seemed to think the turbulence was what made bubbly water dangerous, and not a lack of expected buoyancy. > > _Scubaqueen’s_ story (yuck!) seems to suggest maybe they didn’t go far enough in the test though. For what it’s worth, this is a boat, not a person, but this BBC clip seems to show that gas bubbles can lower the density of water sufficiently to sink a boat. [![](https://img.youtube.com/vi/MSmAXp_BHcQ/maxresdefault.jpg "Sinking a Ship with Bubbles | Bermuda Triangle | BBC Studios") ](https://www.youtube.com/watch?v=MSmAXp_BHcQ) ---
**Author:** ![PlainJain](https://avatars.discourse-cdn.com/v4/letter/p/5daacb/32.png) [@PlainJain](https://boards.straightdope.com/u/PlainJain)\ **Post date:** [July 6, 2011, 6:53am UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/52 "2011-07-06T06:53:18Z")
Here’s [a guy who purports to dive from 125 feet](http://www.youtube.com/watch?v=_h3bhobQdr8&NR=1&feature=fvwp) and basically does a belly flop with no apparent ill effects. ---
**Author:** ![Crazyhorse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crazyhorse/32/31_2.png) [@Crazyhorse](https://boards.straightdope.com/u/Crazyhorse)\ **Post date:** [July 6, 2011, 7:40am UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/53 "2011-07-06T07:40:27Z")
> [@PlainJain](#): > > Here’s [a guy who purports to dive from 125 feet](http://www.youtube.com/watch?v=_h3bhobQdr8&NR=1&feature=fvwp) and basically does a belly flop with no apparent ill effects. Apparently [the same police constable](http://m.timesofindia.com/PDATOI/articleshow/7397004.cms) in that video (ouch) made an attempt at the Guinness Book by jumping from 30 feet into a tank with about 1 foot of water. He belly flopped on that one too. He seems to be quite the sportsman: > [@](#): > > his other achievements include swimming a distance of 82 km in vaigai river in 23 hours, lifting six kg dumbbells 27,000 times in 24 hours, standing on one leg for 81 hours and running 100 km with a sandbag weighing 17 kg. ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [July 6, 2011, 11:04am UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/54 "2011-07-06T11:04:48Z")
When I first saw the Golden Gate Bridge, the first thing that struck me is that it rises quite high before it ever even crosses the shore, like 4 or 5 stories high. It seemed to me that a jumper who really wanted to be certain of fatality should jump from there rather than risking an incomplete attempt into the water. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [July 6, 2011, 11:52am UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/55 "2011-07-06T11:52:16Z")
> [@PlainJain](#): > > Here’s [a guy who purports to dive from 125 feet](http://www.youtube.com/watch?v=_h3bhobQdr8&NR=1&feature=fvwp) and basically does a belly flop with no apparent ill effects. The video mentions “minor injuries,” but doesn’t say anything more detailed. From 125’, the impact velocity is about 61 MPH. That’s a significant decrease from the 80 MPH you would get jumping off of the Coronado or Golden Gate bridges. At 80 MPH, the pressures/decelerations you experience upon impact with the water would be about 60% higher than what the man in the video experienced. ---
**Author:** ![flight](https://avatars.discourse-cdn.com/v4/letter/f/bbce88/32.png) [@flight](https://boards.straightdope.com/u/flight)\ **Post date:** [July 6, 2011, 4:01pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/56 "2011-07-06T16:01:20Z")
> [@Machine\_Elf](#): > > The video mentions “minor injuries,” but doesn’t say anything more detailed. > > From 125’, the impact velocity is about 61 MPH. That’s a significant decrease from the 80 MPH you would get jumping off of the Coronado or Golden Gate bridges. At 80 MPH, the pressures/decelerations you experience upon impact with the water would be about 60% higher than what the man in the video experienced. Where do you get your velocity numbers? I calculate around 70mph impact from 200 feet if you are spread out and 75 if you are feet-first. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [July 6, 2011, 6:38pm UTC](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677/57 "2011-07-06T18:38:59Z")
> [@flight](#): > > Where do you get your velocity numbers? I calculate around 70mph impact from 200 feet if you are spread out and 75 if you are feet-first. Rounding error and a total neglect of aero drag. Sorry. I redid the calcs, including aero drag, and came up with this: 200-foot free fall spread eagle, with drag: 71 MPH zero aero drag: 77 MPH 125-foot free fall spread eagle, with drag: 58 MPH zero aero drag: 61 MPH That changes the impact forces just a bit: only 50% higher for the 200-foot freefall compared to the 125-foot freefall (instead of the 60% higher I reported earlier). That’s still a substantial difference in impact forces. If the constable sustained “minor” injuries during his 125-foot jump, a 200-foot jump would likely cause major trauma. [Previous page](https://boards.straightdope.com/t/what-exactly-kills-you-when-you-leap-off-of-a-high-bridge-into-water/587677.md?page=2)