The yacht was at the isthmus of Catalina Island. I have been there in the summer and went swimming from a sail boat. The currents were strong and carried me pretty far from the boat. I was not drunk and I am a good swimmer, but it took an effort to swim back to the boat. I can understand how somebody who is drunk and in that water on a cold dark November night could drown. Also, she was wearing a thick coat that got soaked. I think she drowned.
Rip tides are savage. I was at the isthmus on Catalina several years ago and got caught in a strong rip tide. Luckily I swam with the rip tide, instead of against it, at an angle and eventually made it back to shore.