Kelp forests are incredible marine ecosystems. Kelp looks like a chaotic disaster on the surface, but under the water resolves into tall, tree-like forms that are full of wildlife. It's well worth making a trip to Monterey, CA (about a 3 hour drive from San Francisco) to see the beautiful kelp forest exhibit at the aquarium there.
If you're a scuba diver, Monterey is also the best place to see this world firsthand. Unfortunately, it can take a few dozen dives before you have a day with clear enough visibility for a real underwater panorama, but once you see it, you'll be hooked.
Be sure to dive with someone experienced, rent proper cold-water gear, and get the briefing on how not to get stuck in kelp on the surface. It's not dangerous, but it can take all the fun out of diving.
A recommendation for the book 1491 (http://www.goodreads.com/book/show/39020.1491). It covers a lot of ground in 500 pages but spends at least a chapter on various theories for how the Americas were first populated (and whether they were populated multiple times). Later chapters focus on major New World cultures. I thought I knew a fair bit about the pre-contact Americas but I learned a lot
No mention of the recent genetic studies that show genetic similarity between deep-Amazon Native Americans and indigenous Australo-Melanesian people, which would seem to support this hypothesis[1]. It seems like there were at least two (actually probably 4) waves of non-European colonization of the Americas - the "Kelp Highway" one described here, followed by the big-game hunters who eventually wiped out that initial wave almost everywhere except in the marginal lands deep in the Amazon jungle. There was also the Athabaskan / Dené and the Eskimo after that.
13,000-15,000 years ago: Kelp Highway settlers
11,000-13,000 years ago: Big-game hunting ancestors of majority of Native Americans (Clovis culture) at time of European contact arrive and mostly wipe out the first wave of settlers except in isolated areas like the Amazon jungle
[somewhere in between]: Athabaskan / Dené come across from Siberia and occupy Alaskan / Canadian interior, as well as parts of the Pacific Northwest and American Southwest (not sure how they got there)
~3,000 years ago: Inuit / Inupiat / Yupik migration and settling of the circum-polar region
If you're a scuba diver, Monterey is also the best place to see this world firsthand. Unfortunately, it can take a few dozen dives before you have a day with clear enough visibility for a real underwater panorama, but once you see it, you'll be hooked.
Be sure to dive with someone experienced, rent proper cold-water gear, and get the briefing on how not to get stuck in kelp on the surface. It's not dangerous, but it can take all the fun out of diving.