# Undersea topography in Google maps **URL:** \ **Category:** Factual Questions\ **Created:** [March 11, 2008, 2:46pm UTC](https://boards.straightdope.com/t/undersea-topography-in-google-maps/440965 "2008-03-11T14:46:54Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Figaro](https://avatars.discourse-cdn.com/v4/letter/f/ea666f/32.png) [@Figaro](https://boards.straightdope.com/u/Figaro)\ **Post date:** [March 11, 2008, 2:46pm UTC](https://boards.straightdope.com/t/undersea-topography-in-google-maps/440965/1 "2008-03-11T14:46:54Z")
My question is…why/how is it visible? If you zoom out enough in Google Maps and look at either the Atlantic or Pacific oceans, you can clearly see the undersea ridges, mountain ranges, and plate junctions. My (possibly ignorant) assumption is that the oceans are nowhere near transparent enough when viewed from space to reveal those details, so I’m guessing it’s a technical property of certain kinds of satellite photography, like the use of non-visual spectra (infrared?, UV?). Can anyone enlighten me? Thanks, ~fig ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [March 11, 2008, 2:51pm UTC](https://boards.straightdope.com/t/undersea-topography-in-google-maps/440965/2 "2008-03-11T14:51:45Z")
No, it’s not real imagery. It’s just a relief map, made using traditional methods (soudings, radar etc). The oceans are just filled in to a uniform blue (away from the immediate coastline - you can see where the joins are) with the relief superimposed. For example, see [here](http://maps.google.co.uk/?ie=UTF8&ll=38.404101,-27.629242&spn=0.619877,1.454315&t=h&z=10). The real satellite imagery on the islands is clear, but the ocean is just a blue fill “draped” over a fairly low-res relief map - you can see the large pixellation of the depth data. ---
**Author:** ![Figaro](https://avatars.discourse-cdn.com/v4/letter/f/ea666f/32.png) [@Figaro](https://boards.straightdope.com/u/Figaro)\ **Post date:** [March 11, 2008, 2:57pm UTC](https://boards.straightdope.com/t/undersea-topography-in-google-maps/440965/3 "2008-03-11T14:57:32Z")
[QUOTE=Colophon] No, it’s not real imagery. It’s just a relief map, made using traditional methods (soudings, radar etc). The oceans are just filled in to a uniform blue (away from the immediate coastline - you can see where the joins are) with the relief superimposed. For example, see [here](http://maps.google.co.uk/?ie=UTF8&ll=38.404101,-27.629242&spn=0.619877,1.454315&t=h&z=10). The real satellite imagery on the islands is clear, but the ocean is just a blue fill “draped” over a fairly low-res relief map - you can see the large pixellation of the depth data. [/QUOTE] Ah - that makes sense. Thanks for the reply. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [March 11, 2008, 3:01pm UTC](https://boards.straightdope.com/t/undersea-topography-in-google-maps/440965/4 "2008-03-11T15:01:24Z")
As for where Google gets that data from, if you zoom to an area of empty ocean, you get “(c) 2008 TerraMetrics, Nasa”. TerraMetrics appears to be [here](http://www.truearth.com/). ---
**Author:** ![Pushkin](https://avatars.discourse-cdn.com/v4/letter/p/ee59a6/32.png) [@Pushkin](https://boards.straightdope.com/u/Pushkin)\ **Post date:** [March 11, 2008, 3:57pm UTC](https://boards.straightdope.com/t/undersea-topography-in-google-maps/440965/5 "2008-03-11T15:57:11Z")
[QUOTE=Colophon] The real satellite imagery on the islands is clear, but the ocean is just a blue fill “draped” over a fairly low-res relief map - you can see the large pixellation of the depth data. [/QUOTE] Woah, don’t [step off Japan](http://maps.google.co.uk/?ie=UTF8&t=h&ll=37.370157,145.195313&spn=14.05653,28.78418&z=5)! ---
**Author:** ![Troy\_McClure\_SF](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troy_mcclure_sf/32/4150_2.png) [@Troy\_McClure\_SF](https://boards.straightdope.com/u/Troy_McClure_SF)\ **Post date:** [March 11, 2008, 5:03pm UTC](https://boards.straightdope.com/t/undersea-topography-in-google-maps/440965/6 "2008-03-11T17:03:05Z")
[QUOTE=Pushkin] Woah, don’t [step off Japan](http://maps.google.co.uk/?ie=UTF8&t=h&ll=37.370157,145.195313&spn=14.05653,28.78418&z=5)! [/QUOTE] I stepped off there once. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [March 11, 2008, 5:05pm UTC](https://boards.straightdope.com/t/undersea-topography-in-google-maps/440965/7 "2008-03-11T17:05:54Z")
[QUOTE=Troy McClure SF] I stepped off there once. [/QUOTE] What year, and how long for?