Whale Watching is a big deal off San Juan Island and that is why we went there on a trip to Seattle.
We saw at least 15 orca whales on our trip with San Juan Safaris. We drove up and used the ferry to get to the island. The ferry ride over was nice too, about an hour. You might want to bring your own food the food on the ferry was from a machine.
The boat tour was about 3 hours, which was just about perfect. After we looked at whales we then went to an eagles nest and saw 3 bald eagles. There were seals along the rocks in several places. We saw lots of birds on the water and some black and white porpoise on the way home. I would definitely recommend this tour.
Equipment: Nice, new boat. Inside cabin felt good as it got a little cold once the boat was going. Big bathroom.
Bring your camera and maybe a snack. There are binoculars and blankets on the boat.
If you are in the islands either get out on the water or IN the water. Winter is a great time to dive up here, and there are lots of great spots. Be careful of strong currents, know what you are doing and dive with a buddy.
Equipment: Bring your cold water gear or drysuit. Or you can rent equipment from Island Dive, which has a shop right down at the Port. They do charters as well.