Cooler Water, More Shark Encounters and the Possibility of Whales

Location: Roca Partida, Socorro, Revillagigedos, Mexico

Comments: Dive Day 4 was at Roca Partida which, thanks to our shore office keeping a sophisticated eye on the weather, we were able to enjoy once again in a relatively low swell. As is common at this time of year, the water temperature is cooling down to a balmy 72F – 74F due to incoming currents and upwellings. As the scuba divers went around “the rock” they felt significant thermoclines, especially at the north and south points where the prevailing currents wrap around. This is also where we encountered the same manta as last trip who came in to interact with the divers.

The upside of this cooling is that the larger oceanic sharks start appearing. We saw a group of 6 silvertip sharks and 4 galapagos sharks patrolling “fish alley” where the large schools of jacks and bonitos hang out. There seems to be a hierarchy in the shark world whereby silkys are displaced by galapagos which in turn are displaced by silvertips. Once again our observations upheld this as we only saw one silky shark off in the distance whereas on our last trip we saw several silkys and one lone silvertip. This behaviour is probably due to the difference in food sources; silvertips and galapagos sharks have a more varied diet including octopus and eels whereas silky sharks tend to prefer ocean going fish such as tuna and of course the flying fish that we see them hunting in our lights at night.

The other upside of the cooler water is that it means the humpback whales are on their way down. We have started to see them off in the distance at San Benedicto and on our crossings so stay tuned, you never know what we will see next.


Weather: Air temperature is at 85F, and sunny with a light breeze and a low swell.

Water: Water temperature is at 72F-74F. Visibility at 100ft.

By Nautilus Staff

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