Not quite a Speedo, but

[Byron]

Not Japanese - the Tao people of Orchid Island off Taiwan.
(unfortunately where Taiwan's nuclear waste products are also dumped).

The great canoe launching is one of three traditional annual ceremonies
and a new fishing boat is put to sea with chanting and dance for a prosperous harvest
of flying fish, to be caught between March and June.

http://www.iov.org.tw/eng/taiwanculture14-2.asp