Probably the best place to do Sea Kayaking is the west coast of Vancouver Island in areas such as Nootka, Barkley, Clayoquot & Kyuquot Sounds. The area feature sandy beaches, numerous small islands and tons of wildlife including whales. Many of these areas have native Indian villages and this is an opportunity to come in contact with them. Some of companies in the table below can arrange things for you. As far as white water rafting is concerned, you can find rivers ranging from easy class 1 & 2 up to class 4 & 5. Most rivers change classification depending on the time of year and the water levels. Probably the most popular run is the Thompson River which is generally a maximum of class 4 with several class 3 rapids. This river runs through a very arid canyon and the high heat tends to offset the cold water of the river. This river can be combined as a 2 day trip with the Fraser River. The Fraser has only a few rapids but it does include the class 5 Hells Gate rapid. Special rafts are required on the Fraser, Hells Gate is actually close to a class 6, but with the boats used and the specially trained guides, even a novice can do it. The Nahatlatch is a class 4 and class 5 river. I have not tried it yet, my recent near drowning experience in the Zambezi River in Zimbabwe has made me a little shy, but they say if you can raft the Zambezi, you can raft anything. Rafting in BC is highly regulated and as safe as possible, but fatalities have occurred. Check with your Travel Insurance to make sure you are covered for this activity.

The most popular canoeing route in BC is the Bowron Lakes circuit. You need about 8 days to do this. The start point is about 40 km from the historic town of Barkerville. Go to this link for info http://www.env.gov.bc.ca/bcparks/explore/parkpgs/bowron_lk/ . Also check out the link to Fresh Tracks below if you want to do it with an organized tour. If you want to do something a little tamer, try renting a canoe at Lightning lake Picnic ground, about 60 km east of Hope on Highway 3. This is a pleasant one day excursion and is beautiful. It is very difficult to get into the campground there, go to my camping section and click on the BC Parks link to make a reservation.

Wade Holidays Rafting in Squamish, just north of Vancouver
Lotus Land Tours Kayaking for softies
Sea Shell Diving & Kayaking Near Courtenay, BC on Vancouver Island
Wedge Whitewater Rafting Whistler
Liquid Lifestyles White water rafting in Clearwater (near Kamloops)
Sea Kayaking Vancouver Island - Wildheart Adventures  
Sea Kayaking Tours (Out for Adventure) Tours in BC & Ontario - Whale watching, etc.
Sea Kayaking Tours - Coastal Spirits, Canada Sea Kayaking, Whale Watching
Elaho Adventures Rafting & Eagle watching, Whistler
Kayaking tours Vancouver Island Including Whale Watching
Sea to Sky Expeditions Sea Kayaking / Rafting - Northern BC
Kaslo Kayaking, Kaslo, BC, Canada Based in the Kootenays SE BC
Natural West Coast Adventures - Kayaking and Paddling Vancouver & Victoria offices
Ecomarine Ocean Kayak Centre Courses, Resources
Guide for Hiking, Skiing, and Canoeing in BC Excellent Resource
Bowron Lake Provincial Park Info on this popular canoeing area
Bowron Lake Provincial Park Information As above, including German language sections
Emerald Sea Expeditions Sea Kayaking, Whale Watching Vancouver Island
Spirit of the West Kayak-Adventures Sea kayaking
Batstar Home Page Sea kayaking on Vancouver Island
Cormorant Seakayaking Sea kayaking on Vancouver Island
Tofino Expeditions Sea Kayaking Sea kayaking on Vancouver Island
Canadian Voyageur Canoe Company Canoe Tours Whistler/Pemberton
whitewater.org White Water Kayaking Association of BC
Fraser River Raft Expeditions White Water rafting
C3 Rafting White Water rafting Whistler area
Wedge Rafting White Water rafting Whistler area
Canadian Outback White Water Rafting, Sea Kayaking, etc
Purcell River Odysseys Rafting & Kayaking in the Kootenays
Kayak Adventure Tours Kayaking
Majestic Ocean Kayaking Kayaking-Vancouver Island
Deep Cove Canoe and Kayak Kayaking in Vancouver
Gulf Islands Kayaking Kayaking-Galiano Island
River Rafting with REO One day rafting, week long river trips, wilderness adventures
Whistler River Adventures Boat Trips, rafting
Kumsheen Raft Adventures White Water Rafting
Hyak Wilderness Adventures White Water Rafting
Whitewater Rafting on Vancouver Island White Water Rafting
Stellar Descents White Water Rafting - Northern BC
Rafting on the Kispiox and Skeena Rivers White Water Rafting - Northern BC
Chilko River Rafting Near Williams Lake
Clearwater Lake Tours. Canoeing in Wells Gray Park
Viking Adventure Tours Kayaking, Diving, Whale Watching
Kayak Whistler Learn to Kayak in Whistler
Fresh Tracks Adventure Tours (Bowron lakes + more)
Baja Outpost Kayaking in Mexico's Sea of Cortez