Vancouver Island, is the largest island on North America's west coast. It is approximately 500 km long, with an area of some 32,100 square kilometres and 4% or about 1,200 km2 of this surface area is karst. This represents just over 0.1% of the total carbonate rock surface in Canada or 1,200,000 km2 (about the same as China).
The caves of Vancouver Island are comparatively well developed due to high rainfall, dense vegetation, soil cover, and mountainous topography. There are more explored limestone caves here than in all other Canadian provinces combined. Vancouver Island is so rich in caves, with more than 1,000 recorded, that it is sometimes referred to as the "Island of Caves".
There are more explored limestone caves here than in all other Canadian provinces combined. Some of Canada's longest and deepest cave systems are found on Northern Vancouver Island. There, hundreds of caves have been survey since systematic exploration began in the early 1970s, including some with over 10 kilometres of mapped passages.