You can rent a boat and a El Capitan from any hotel. Our cost was $120.00 US, and we were out for about 6 hours. The Captain (Benjamin) was an experienced fisherman who has lived in Bahia his entire life. I recommend asking for him. It was too cold outside for yellowtail, but we caught several dozen Bay Bass, squid, codd, and we even picked up a bucket of clams.
This has to be one of the top places in North America for Kayaking. There is so much to see. There are an abundance of whales, dolphins, birds, and all kinds of fish. The views of the surrounding desert are spectacular.
You can either bring your own Kayak, which I recommend, or easily rent one from any hotel and most camp sites. If you rent ensure the structural integrity of the Yak...there is nothing worse than paddling a giant piece of plastic filled with water.
Next, bring an Ice chest. Fill half of it with water and the other with food and beer. Expect to be out all day. There is so much to explore.
Bahia de los Angeles has a small but interesting museum that has displays on the local natural history, anthropology, and the history of the settlement of Baja California, which is actually very interesting.
If you a birder, Bahia has alot to offer. I'm a not a birder, so I can't offer the specifics in this tip. There were several student doing surveys while I was there.