Check out sbchannelswim.org. 2 competitive events this fall: 6x6 relay from Santa Cruz Island to East Beach Sept 5-6; 10 mile Pier to Pier Sept 21 (details not on website yet). Also see Oceanducks.com. Weekly non-competitive swims of increasing distance throughout the summer. Currently 3+ miles on Saturdays, 1-2 miles on Sundays.