I spent two weeks (March/April 2006) in Baja California (mostly Sur), Mexico with two friends from school, Phil and Sean. Our primary goal was to have an awesome spring break, but Phil also did some limpet-measuring work and we all made good use of the half-ton of natural history books we brought.
Perhaps our most amazing activity was seeing grey whales up close in Laguna San Ignacio (the cute sign is actually from Ojo de Liebre, a bit further north). By the time we got there, the males had already left, but we saw ten or so mother-calf pairs (middle photo). And they were friendly and came right up to our little boat!
Sean caught us some herps: Urosaurus nigricaudus, Crotalus ruber, Coleonyx variegatus, Ctenosaura hemilopha. Watch out, this guy bites tenaciously!
We found excellent snorkeling on the Gulf side around Puerta Agua Verde and Cabo Pulmo. Too bad I don't have an underwater case for my camera, but we saw tons of beautiful fish (the pufferfish were my favorites), stripey moray eel, octopus, guitarfish, and plenty of stingrays. Lucky Sean spent part of his birthday swimming with a sea turtle!
The cardón is a massive cactus which replaces the saguaro in the southern Sonoran desert. Raptors hang out on their tops (two caracara and a turkey vulture above). Because of their height, it's hard to get a good flower photo -- this was the only conveniently-placed one we found.
My favorite from the whole trip was the boojum forest. I arranged my cot so I would wake up and instantly see some over me. These are crazy plants, and with quite a small range.
Overall, it was a fantastic trip! Definitely try to experience Baja for yourself before it gets as overdeveloped as southern California....