A Dolphin Escort to Cocos Island

Greg Stone is on his way to take part in a National Geographic expedition exploring seamounts off the coast of Costa Rica. Check out his previous posts from the trip.

Bottlenose dolphins swimming in the bow wake of a boat near Cocos Island, Costa Rica. (© CI/Photo by Greg Stone)

I awake to the bright morning sun streaming through my cabin’s porthole, wishing that I’d taken a cabin on the starboard side of the ship, pointing west. After pulling on a pair of shorts and a T-shirt, I am out the door and up the companionway, finding myself in the galley where several crew members are watching television.

The cook indicates he can make me some food, but he speaks little English. Soon I have ordered an omelet — or at least I think I have — and leaving him to cook it, I open the heavy watertight door, step over the bulkhead and walk out on the deck.

Squinting in the bright sunlight and feeling the intense warmth of the tropics, the smell of the ocean fills my senses. The air has a rich, full humidity, lightly spiced with sulfur — specifically the dimethyl sulfide that is produced by trillions of microscopic plants in the ocean that now surrounds me. These tiny plants produce most of the oxygen on Earth — creating the atmosphere on which we depend — and are the photosynthetic basis for the entire ocean food chain.

I see a white fleck in the distance: the hull of a fishing boat. The ocean is flat, like a mirror, as our vessel cuts a line through it, making a wake that stretches out on either side as far as the eye can see. A flying fish leaps from the water, and we make eye contact. A sooty shearwater (Puffinus griseus) bobs in the water, looking up as we glide by. Not a cloud in the sky, the ocean is a silvery blue. I am home.

Early the next morning, Cocos Island is in view — the most spectacular island I have ever seen. Multiple peaks rising from the ocean, waterfalls stream into the sea, flocks of birds feed and bottlenose dolphins (Tursiops truncatus) surround us. I can hear their high-pitched screeches as they jump, twist and play in the ship’s bow wake. I spend an hour with them as we pass Cocos; then as if to say “goodbye,” they leap, tail slap and head back to the island.

Greg Stone

These dolphins are generally found along the coast and near islands. The seamount to which I am heading — some 30 miles [48 kilometers] beyond Cocos — is too far off shore. I look to the horizon, hoping to see the boat where I will meet my colleagues, but she is still too far away. The captain says we will rendezvous in some eight hours; I cannot wait.

Greg Stone is CI’s chief scientist for oceans. This expedition is 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. Check out the next post in this series.


  1. Kathleen Zuniga says

    It’s amazing that there are little plants in the ocean that produce a majority of the oxygen that we breathe each second. More people should be educated about the world around us, and the science behind our daily behaviors. A whole new appreciation is formed.

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