Water clarity in the Northwest is usually best during cold months when plankton dies off, but the weather is far more comfortable in summer, and even in August you can usually avoid the worst of the plankton blooms. Early fall can be a pivotal time, with warm, clear weather but better water visibility. For that reason, September and early October are very popular dive months in the Northwest. Diving in Canada is dirt cheap by U.S. standards. Half day, two-tank trips run $65 to $70 CDN. Head-to-toe rentals for wetsuits run about $60 CDN (which works out to $40-$45 U.S.). Live-aboard dive boats run $130 U.S. a day, and dive lodges run about $95 U.S. a day for bed, meals and heavy gear. If you're staying on land and plan only two dives a day, you can probably make it in a wetsuit. But water temperatures are commonly in the 40s, and for serious diving a drysuit is preferred.