Definitely bring water. We didn't camp there, but we stayed for several hours, walking the trails and going in one of the caves. The cave was great even for people who don't like caves (me) because the top had caved in at points so there was always light, and you can crawl out the other side.
Super cheap museum. It's a little small, but everything in there is high quality. There's also a bit of everything. It's well worth seeing.
There is such a cute little octopus thing. Then there's actually a real octopus who is also really cool. The best part is feeding the seals. If you stay at a local hotel, many give you a coupon for a free thing of seal food.
This is good if you're a Goonies fun, but be aware that due to rude tourists, the house owners no longer allow visitors. There is a good view from downtown. If you stop to look at the sea lions, you can see it from there.
The bird was in bad disrepair when I saw it, boards falling off and everything. It was a cool, but the main fun is in the mall. There's this fun little glow mini-golfing when you walk in. There's also plenty of stores. It's like a giant, permanent yard sale in there.
This is gross as many other people said, but it's free and worth a picture. While you're there, offer to take someone else's picture. It's worth the time.