The primary attraction of Bowen Island to Vancouverites has been to get away from everything and relax. If you want to "do" something however, there are a few options.
One is to rent a kayak and paddle around Snug Cove or venture around the island. Bowen Island Sea Kayaking, on the ferry dock at Snug Cove, 604-947-9266 [email protected], (http://www.bowenislandkay...), rents kayaks by the hour or overnight. They also provide lessons and guided tours. $35/$45 single/double, for three hours.
There are also a number of hikes on the island. Crippen Regional Park offers a number of shorter hikes that can be done in a couple of hours. Dorman Point trail begins at the end of Snug Cove beach provides views of the harbour and the entrance to Howe Sound. The hike to Killarney Lake about 45 minutes each way passes through forest and the fish ladder to the lake. There is also a 4 km hike around Killarney Lake.
Tougher, but with more rewarding views, is the hike to the top of Mount Gardner. The trail begins 3 km from Snug Cove on Mount Gardner Road and is mostly through forest. It rises to an elevation of 719 m and on sunny days provides a very nice view. The trail is 11 km in length, so be sure to leave yourself enough time if you have to walk from Snug Cove to the trailhead.