He lucked out. Catalina is about 22 miles off the coast of California, specifically Orange County. Very well traveled - there are probably 20 ferries daily. And probably dozens of private vessels too.

Unfortunately, nearly the entire island traffic goes to Avalon, at the southern tip. There's a Boy Scout camp halfway up the island at the isthmus, and one at the northern end (Emerald Bay). Also a girl scout camp. There's also a small airport, serving Cessna-type planes.

I assume there's LOTS of flashes - it IS the ocean, after all. totally normal to ignore one.

The other interesting, and perhaps frustrating thing, is that he's probably within site of land. Certainly, from the beach on a clear day, you can see out to the island. From any altitude on the island, you can see the mainland (and all the ocean in between). Literally, hidden under the noses of thousands (milions?).