its very popular for tourists to take a sunset cruise in vancouver...for the cost of two seats on a boring cruise, you could rent a little speedboat from granville island rentals (or stanley park boat rentals)...try speeding out to bowen island and tying up on the public dock...walk past the pubs near the dock up the hill to the bowen island pub which brews their own delicious beer
if its windy, try the protected waters in spectacular indian arm...its accessible from vancouver harbour...great spot to spend a few hours exploring or finding a place to have a secluded picnic ashore
Stanley Park Boat Rentals, Coal Harbour Marina, 566 Cardero St., 604-682-6257
Granville Island Boat Rentals, 1696 Duranleau St., 604-682-6287
more vancouver waterfun info here:
http://www.nwsource.com/travel/scr/tf_detail.cfm?dt=3695&cid=6&pageid=BC&cityid=90oh yeah, if you're visiting vancouver, you must check out wreck beach...its vancouver's 'clothing optional' wormhole to the 60's (please don't bring a radio or camera)
http://www.wreckbeach.org/