Leave the iPod at home and hit up your local thrift store for a handheld transistor for this afternoon of pleasure boating and pirate-radio beats. East Bay civic-pride squad Oaklandish arranges for half-priced boat rentals all afternoon. While you're swanning about in your craft, local DJs broadcast their vinyl treasures on a special micro-frequency, Youth Spirit Artworks holds a silent furniture auction, and Linden Street Brewery provides ample suds. For the less athletically inclined, limited free pontoon and gondola rides are available. Who needs Venice when you have Lake Merritt?