The "Canyon" biome is now available for testing as an optin beta.
The canyon area contains a single race track and is fairly sparsely decorated at the moment. However, it does give a taste of the type of races that will be available in this area which will be tight, technical courses on calm waters.
The canyon area is located at the very South East corner of the map and can be sailed to from the Tropical Islands biome if you wish. However, the quickest way to get there is to start a race, select the new "Canyon Run" track, and then quick the race. You'll remain in the canyons and can then explore as you wish.
Feedback, as always, is very much encouraged via the Steam forums.