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!

EDIT - here's a preview:

"Diana Botutihe was born at sea. Now in her 50s, she has spent her entire life on boats that are typically just 5m long and 1.5m wide. She visits land only to trade fish for staples such as rice and water, and her boat is filled with the accoutrements of everyday living – jerry cans, blackened stockpots, plastic utensils, a kerosene lamp and a pair of pot plants.

Diana is one of the world's last marine nomads; a member of the Bajau ethnic group, a Malay people who have lived at sea for centuries, plying a tract of ocean between the Philippines, Malaysia and Indonesia. The origins of the Bajau diaspora are recounted in the legend of a princess from Johor, Malaysia, who was washed away in a flash flood. Her grief-stricken father ordered his subjects to depart, returning only when they'd found his daughter."