Chris’ Dive Experiences: Roca Partida, Socorro Islands MX

Roca Partida sits about 70 miles west of its closest neighboring island, and is 350 miles south of Cabo San Lucas, your launch point for your journey to the Socorro Islands. It is the smallest of the Isla Revillagigedos (otherwise known as the Socorro Islands) at only 3.5 acres. What the island lacks in land mass it makes up for in underwater marine life.

Being so small and sitting out in the middle of the Pacific, this site can either be very calm or completely undivable. On this particular morning in March, we were awakened by the clatter of kitchenware falling, along with a myriad of other things flying around the boat, as it was rocked by a very large swell on its approach to the island.

Loading into the zodiac was a little challenging because of the large swells rolling through. Once underway we slipped into our gear, timed our approach to the island with the swell and performed our negative back-rolls off the side of the zodiac in unison, then met up underwater.

As I descended down to 118 feet I took in my surroundings. Roca Partida underwater was a sheer wall as deep as the eye could see, mostly covered by urchins. There were crevices  carved into the wall at various depths, each of which seemed to be packed with white tip sharks stacked on top each other and huge trophy sized spiny lobster. Once I peeled my eyes off of the life on the amazing wall, I noticed the water surrounding the island was in action overload. Even with the 80 feet of visibility, it was hard to see very far due to how much life was enjoying the current sweeping past the island. You could almost fall into a trance by the movement and flow of all the marine life in the remarkably blue water, all the while being serenaded by the passing humpback whales whose singing could be heard throughout the entire dive.

As we neared the southwest corner of the island, the current was slamming into the wall, creating very strong down currents.  So strong that you had to kick with all your might while at the same time inflating your BC so as not to be shoved down beyond your depth limits. Once we stabilized ourselves by finding a sweet spot along the wall with minimal down current, we could enjoy the show taking place in front of us.

Off in the distance was a huge school of scalloped hammerhead sharks closing in toward us. In no time they were over our heads, then again fading off into the distance. We were in awe of the close passes by silky, silvertip and Galapogos sharks as we swam along the wall. Mixed in this marine life parade were huge jacks keeping pace with the sharks. As we started our slow ascent up the wall, we were greeted by an enormous pacific manta ray with a wingspan that must have been over 20 feet. Sweeping right over our heads, this manta seemed to love being caressed by our expelled bubbles on its belly.

It is generally standard practice of boats travelling to the Socorro Islands to spend 2 days diving Roca, but due to the large swell and strong currents we were only able to stay for less than a day and only get to do 3 dives. Despite that, we were rewarded with lots of big animal encounters and a challenging but very rewarding set of dives that we will never forget.

Photo credit: Norbert Probst

Creature Feature: Banded Sea Krait

The banded sea krait is an amphibious species of snake, closely related to the Asian cobra, that spends most of its life at sea but comes to land to digest its food, shed its skin, and to reproduce (able to spend up to 10 days at a time on land). Sea kraits are often spotted along the coasts of the eastern Indian Ocean, east through Malaysia, Indonesia and Papua New Guinea to islands of the south-western Pacific, and north to Vietnam, southern China, Taiwan, and the Ryuku Islands, Japan. Occasionally you may see them in the waters off Australia and New Zealand, or as far as the western coast of Central America. The banded sea krait is usually found hunting for food in shallow tropical waters surrounding coral islands, coral reefs and mangroves, to depths of around thirty feet (but some species may dive up to 100 feet). Some species prefer hard bottoms (corals), while others prefer soft bottoms (mud or sand) in which to hunt their prey. Most sea snakes feed upon fishes of various sizes and shapes, including eels.

The sea krait's body has evolved to adapt to its curious semi-aquatic lifestyle. Like its brothers the terrestrial snake, it has larger scales on its underbelly and a cylindrical body shape to aid in climbing onto land and in low trees, but its tail is paddle-shaped to help it speed through the water. With valved nostrils to keep out saltwater while diving, the sea krait has a large lung capacity so that it may stay under for extended periods of time, and glands under its tongue that expel excess salt. The head looks similar to the tail in order to confuse predators and draw them to attack the tail which is less likely to inflict fatal injuries.

On land, the sea krait finds shelter in vegetation, under beach rocks, in caves and crevices. It is in these limestone caves and crevices where they go to lay their eggs; generally a deposit of 1 to 10 eggs. Males come ashore early in the evening and eagerly await the arrival of a female at the high tide waterline. Upon her arrival, several males will wind themselves around the female and escort her to shore. The female can be distinguished as being heavier and around a third longer in body size than the male. A sea krait's average length can range from 3 to 4.5 feet.

Although their venom is the most potent of all snakes, human fatalities are rare because sea snakes are not aggressive, their venom output is small, and their fangs are very short. The longest living sea krait in captivity on record lived to be seven years old.

[1] ARKive: Images of Life on Earth, http://www.arkive.org/banded-sea-krait/laticauda-colubrina/

[2] Britannica Online Encyclopedia, http://www.britannica.com/EBchecked/topic/530726/sea-snake