What could be better than combining an active adventure with the chance to see some of the planet's most precious animals? How about swimming with a shark the size of a double-decker bus? The huge yet gentle whale shark is the biggest fish in the ocean and, arguably, the most lovely with its expansive flat back, spotted white like a starry sky. Dive with these big beauties in Mozambique - they sometimes congregate in groups of up to 50 to feed on plankton off pretty Tofo beach. You'll find Diversity Scuba (00 258 2932 9002; diversityscuba.com) and Tofo Scuba (00 258 82 826 0140; tofoscuba.com) tucked among the straw-shaded bars and backpacker's lodges. Diving sessions from 1,800 metical (£30) and 1,300 metical (£22) respectively.
In the Canadian Rockies, you can roam with the wild beasts of storybooks such as elk, wolves, and grizzly bears. The best way to explore this expansive wilderness is in the saddle, cowboy style. Guides at Siwash Dude Ranch (001 250 395 6541; siwashlakeranch.com; from C$2,985/ £1,472 for three nights, excluding flights) take you deep into the woods on winding trails and out for a gallop on the open prairies. Or if you're desperate to see a grizzly teach her cubs to fish, Tsylos Lodge (001 800 487 9567; tsylos.com), in the remote Chilko area of British Columbia offers week-long bear-spotting holidays. Catch a plane over the Pacific Coast Mountains from Vancouver to their remote, luxurious wooden lodge and spend a week tracking bears, as well as horse-riding and canoeing, for C$4,495 (£2,882).
The magically named Bwindi Impenetrable Forest, high in the uplands of south-western Uganda, is home to one of the most vulnerable animals. It's a tough hike up from base camp to visit the 320 glossy black mountain gorillas which nest in low trees under a blanket of misty jungle. You need a permit to track them (around US$600/£385) as visitor numbers are tightly controlled, but most operators will organise one for you. Rates vary by season but Gorilla Tours (00 256 414 200221 ; gorillatours.com) has a three-day trek from US$620 (£398), including lodge accommodation but not flights.
Closer to home, the windswept Isle of Mull, off the west coast of Scotland, is a bird-watching heaven. Brave the midges and you'll be rewarded with rugged seascapes and huge seabird colonies. Golden and white-tailed eagles are the grand prize when good weather comes, but any day spent out walking will reward you with ducks, otters and myriad species of seabirds. Mull Wildlife (01681 700090; mullwildlife.co.uk) offers day tours along the island's 300 miles of coastline and precipitous cliffs from £42.