I used to fish there in the 80's. I had a Calsport 22' Super Panga. We would launch at the new port south of San Felipe BC. On a calm day it was a quick run to La Roca. The environment is similar to Isla San Jorge with shallow sand flats surrounding La Roca and a deep swale on the south side carved out by the radical tidal movement. The hole was rocky just like the slopes of the rock. In those days the waters there were loaded with groupers, mostly Sardineros. Lots of Sierras and if I was lucky a huge Wolf Eel that would take a hooked grouper as if was a sardine. Some that I brought in were over six feet long and a superb delicacy. I had those huge alien looking heads nailed to the ramada over my pool deck that would just blow away my guests. They couldn't believe they came from the upper gulf. Probably not much has changed there since the trawlers won't go near it for fear of loosing their gear to the rocky bottom. It is a bird shit covered rock but I think the only ones that nest there are the little Sooty Petrels that live in holes and only come out at night.
I've fished it in the past out of San Felipe with mixed results. The hole on the south side is one of the deepest spots in the northern Cortez at over 600 ft. As we were cruising in close, there was a marlin laying and sunning in a very shallow spot between the rocks. Amazed me! Mostly caught monster size triggers with the kids on board.