What were these holes we saw on the beach in Hawaii?

Okay, I have not posted here in years. But my friend and I had this strange experience a few years back on Oahu. I thought maybe someone here could tell us what we saw. We were in the North Shore area, a little before Waimea Bay if you are coming from Honolulu. Another time we were at Sandy Beach, which is beyond Hanauma Bay from Honolulu.

The thing we saw at both places was the same.

Okay, this is going to sound crazy. The first time we saw it was early in the morning and the beach was nearly completely smooth and empty, we could clearly see the long trail our footsteps left as opposed to everywhere else, which was clean windblown, even sand.
In the sand was a series of indentations, shaped like half-spheres, about the size of a golf ball (no dimples though) the inside of each indentation was perfect and smooth, very very pristine and immaculate looking. These indentations traversed a meandering path, sometimes looping onto itself, seeming randomly. There were no footsteps to be seen anywhere around these indentations, except ours. Yet these indentations were so clean and sharp edged, they looked like they had only been there for an hour at most. That’s a total WAG. But they were VERY fresh-looking and well defined, in any case.

We saw the same thing at Sandy Beach, but this time in a more populated area, but again it looked impossibly perfect. We destroyed a few of them and there was nothing atypical about the sand surrounding them (we did this the first time too).

We talked about it at great length, and concluded that due to the PERFECT spherical indentations, this could not be a natural feature, it had to be man made or machinated in some way. We cannot figure out how it would even be done. We posited a wheel at the end of a stick with spokes coming out of it at regular intervals, each with a sphere at the end, being rolled along the ground, resulting in the described indentaions. The person wielding this instrument would have to not tread on the sand, so we posited that he was maybe in some kind of hovercraft, but if it generated wind it would likely mess up the results. We went to some kind of hot air balloon technology.

Of course none of our hypotheses make any sense at all- what purpose would it serve?

So- can anyone tell us what we saw, what purpose it served (maybe none at all, maybe it’s a by-product of a different process- but what?), or how it was made?

Perhaps there is a simple explanation.

If it makes a difference, this was in 1998 or so.
Thank you!
-Bamboo Boy

My WAG-ant lions or a similar species? This is a view of some of their ant traps, albeit in a much rougher/dirtier type of sand than you likely saw.

Thanks for the suggestion, but it didn’t really look like that, it didn’t have a hole in the center, it was PERFECTLY (to the naked eye) semi spherical in shape, and it was definitely laid out in a linear pattern, which was not a straight line, but a lazy, meandering line, it covered a large area, the squiglly line may have been 5 meters or so. Just guesstimation, but it was in that area.

Those by contrast looked sloped and conical. They look like a natural formation. This was very perfect looking in shape and form. I really really don’t think it was a natural feature.

-Bamboo Boy


My thought as well. When clams dig, they’re displacing sand, which collapses behind them leaving a dimple on the surface. Casual digging at the spot will reveal nothing, as they rapidly move away from a disturbance and in the direction of the ocean.

No, I don’t think they could be anything like that if for no other reason they were very far from the water. Also, like I keep saying, they were SUPER perfectly formed. Think of how sand looks when you fill a paper cup up with sand and invert it creating a perfect cup shaped thing- It had those kind of sharp edges, it was very very clearly defined and perfectlly semi-spherical to my eye, and obviously not a natural feature.

Also, they were laid out in perfect intervals (maybe I failed to mention that detail actually), following a meandering but basically linear path.

So I think clams are really not a possibility.

Thanks for the input though.

Maybe someone with a pegleg walked by? After a short time, the relatively shallow footprints would be obscured, while the deeper pegleg holes remained.

(OK maybe it was someone with a cane, but isn’t it cooler to think of some salty pirate with a pegleg walking around, looking for his treasure?)

Thanks for the laugh, but it was definitely not the work of a peglegged pirate (or regular person…or whatever).

Was the sand still damp as if the tide had recently gone out or was it perfectly dry on top?

it was a LITTLE moist, it wasn’t like sand in an hourglass. But not with seawater, this was (in both cases) a good ways from the shoreline. At Sandy Beach, it was right near our car, near where the asphalt meets the sand.

Can anyone address how perfectly spherical they appeared or the layout (lined up along a squiggly line at even intervals)? It really was like some wheel was being rolled and leaving these perfect indentations…

Crabs? I was in Guam at Christmas, and saw a phenomenon somewhat similar to what you described. I asked someone who lived locally, and he explained to me that the crabs spend the day buried under the sand, and come out at night. In Guam (Tumon Bay), the holes were visible as tunnels down into the sand. However, it’s easy to imagine that with a slightly different consistency of sand, the entrance of the hole would fill in, leaving only a depression like you saw.

If the water washes over a depression in sand it soon becomes spherical. Very round. So, in my experience (CA not HI) footprints eventually appear as spherical holes after the water has washed over them.


What are Buckeyes?

Would crabs make a pattern that very very very clearly resembles a path along a squiggly line, though?

Ditto for footprints, and I have to stress that these were extremely extremely perfectly formed with no imperfections, the surface was perfect and the shape was also (to the naked eye) perfect.

Was it possible that what you saw is the result of a machine groomed beach? Wasaga beach here in ontario, does several passes to give the sand a more touristy look so no and cleans up any aquatic fauna that washes ashore.

I can remember being in virginia beach and myrtle beach and they had all these portugese men of war lying here an yon, and being cautioned not to accidently step on one.


Almost all the beaches on Oahu are cleaned, levelled and ‘groomed’ using driven beach cleaning machines. Most of this activity takes place late at night as far as I know. I saw beaches being cleaned at 11pm, and the path followed by the driver was more meandering than the straight, parallel ‘ploughed field’ lines you might expect.

Although I can’t offer a complete explanation, and we don’t (with respect) have a lot of data to work on, it seems likely that the indentations you saw were somehow left behind by one of these machines or an attachment.

that sounds like the most plausible thing so far…Though I would kinda expect a dual track, running parallel.