I don't know if this has ever been mentioned here or on the old site, but I was surprised to read recently about a culture in Malaysia called the Bajau that is entirely sea-based, just like our friends the Sea Folk:

http://www.guardian.co.uk/environment/2010/sep/18/last-sea-nomads

And apparently there are a few other similar groups, though with a bit more land life mixed in, it appears:

http://en.wikipedia.org/wiki/Sea_Gypsies

Anyway, neat!