Button Bay is a reef site located northwest of the main river mouth near Churchill, Canada. It is distinguished by visibility that is generally superior to the nearby estuary. Divers access this site by boat, and it is suited for advanced divers due to the challenging conditions. The environment is characterised by moderate currents and extremely cold water temperatures, which range from -2C to 8C throughout the year. The site supports a variety of regional marine life, including various reef fish and invertebrates typical of this cold-water habitat. Hazards include low visibility, strong currents, and the risks associated with extreme cold water.

Prince of Wales Fort (Waterfront) is a marine site located in Canada near Churchill. This reef site is accessed by boat and is suitable for intermediate snorkellers. The average depth is 4 metres, with a range of 4 to 5 metres. Conditions are challenging, with moderate currents, visibility ranging from 1 to 6 metres, and cold water temperatures between -1C and 10C. Thick wetsuits are required for all water activities. Hazards include boat traffic, cold water, and low visibility. The site offers parking, toilets, and guided tours for visitors. A typical session lasts 60 minutes.

Sloop Cove is a sheltered location on the west bank of the river, historically utilised by the Hudson's Bay Company. It offers a calmer environment for snorkelling compared to the main estuary. Access to the site is by boat, located 3200 metres from the shore. Conditions are characterised by mild currents and low visibility, typically ranging between 1 and 5 metres. The water is extremely cold, with temperatures fluctuating between -1°C and 10°C throughout the year. Wetsuits are essential for all in-water activities. The site is suitable for beginners, though users should remain aware of boat traffic and the challenging cold water conditions.

The Churchill River Estuary in Canada is a unique site where the river meets Hudson Bay. This location is primarily accessed by boat, which is required due to the nature of the environment. Snorkellers should be prepared for challenging conditions, including strong currents, low visibility, and very cold water temperatures that range from -1°C to 10°C throughout the year. A thick wetsuit or drysuit is essential for safety in these temperatures. The site is rated for intermediate snorkellers, and typical sessions last up to 120 minutes. Hazards at this site include boat traffic, cold water, low visibility, and strong currents.