Cocos Island Seamounts: The Final Dive

This is Greg Stone’s final blog post from a National Geographic expedition exploring seamounts off the coast of Costa Rica. Check out previous posts from the trip.

Avi Klapfer and Greg Stone begin their descent to the seamount in the submarine. (© CI/Photo by Greg Stone)

Today the ocean is flat-calm, reflecting the towering cumulus clouds like a mirror. I don’t think I have ever seen it this calm in all my years at sea — not a breath of wind or ripple of swell. Far to the northeast, I can just make out one of the peaks of Cocos Island, some 30 miles [48 kilometers] away.

Beneath us is the seamount that we have made home this past week. Although it towers 3,000 feet [914 meters] from the seafloor, you would never know it from the surface — the ocean does not give up her secrets easily. To see it, we must use a submarine; I have just completed my fifth and final dive.

The ballast of the submarine was emptied and voluminous amounts of air poured out, racing for the surface as ship captain Avi Klapfer began our descent. Sinking down at 32 feet [10 meters] per second, the murky image of the seafloor gradually came into view. To my right I saw what looked like the boiler of an old ship, a ship similar in size to Titanic. We joked that perhaps we had discovered a new wreck, but in reality this magnificent structure is probably a volcanic remnant, perhaps dating back millions of years.

The submersible Deep See lands on the summit of a seamount near Cocos Island. (© CI/Photo by Greg Stone)

The thrusters whirred and Avi made the sub spin on a dime. “The current is strong,” he told me, making it doubtful we would be able to explore much further. But within minutes, Avi maneuvered Deep See into the lee of the conical lava tube, and we photographed spotted and olive groupers. Many rays glided by but were too swift for us to capture on film.

I never tire of seeing what the ocean has to offer. Each day is different and all days are good. It reminds me of what Teddy Tucker, a fellow ocean explorer and my great mentor and friend, once said: “All days on and under the water in the ocean are good, but some are better than others.”

It is estimated that the ocean contains between 10,000 and 100,000 seamounts on a similar scale to this one. If we include the smaller ridges, hills and banks, there are millions of undersea features, most of which have never been explored.

In just a 10-day trip, what we’ve seen has been nothing short of remarkable. Using the remotely operated vehicle (ROV), the submarine and bluewater diving, we have uncovered the animals that live on the summit of this seamount, the pelagic invertebrates that occupy the water column around it. And none of it would have been possible without our fantastic crew of scientists, photographers and sub pilots.

Greg Stone

Our sub surfaced all too soon. We stored our gear and began the long haul back to Puntarenas — and our land-locked lives — where we will analyze our data and add one more puzzle piece to that fabulous mosaic that is our global ocean.

Greg Stone is CI’s chief ocean scientist; photos from this expedition will be published in an upcoming issue of National Geographic magazine. This expedition was supported in part by the National Science Foundation under Grant No. DRL-1114251. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the writer and do not necessarily reflect the views of the National Science Foundation.


  1. Tim Upham says

    Some wildlife are found only on seamounts, such as black oreo and blackstripe cardinalfish. Also, seamounts are made of volcanic rock, which is harder than the sedimentary rock found on the sea floor. This supports suspension feeders, such as coral. Sediment will accumulate more on seamounts, and this provides habitat for annelid marine worms, microdrile worms, and sea slugs. It is a good thing that the ecosystem of seamounts is being studied, so that way we can truly understand how the geology in the ocean shapes oceanic life.

Leave a Reply

Your email address will not be published. Required fields are marked *