The moose (Alces alces), the largest member of the deer family, is often pictured as a creature of the forest and snow, but it possesses surprising aquatic capabilities. Despite its massive terrestrial appearance, the moose is an exceptionally strong swimmer and a proficient diver. This large ungulate routinely enters lakes, ponds, and rivers, fully submerging itself in a behavior unique among most large land mammals. This mastery of water is an adaptation that allows them to thrive in diverse northern ecosystems.
Actual Diving Depth and Duration
Moose plunge beneath the water’s surface to access submerged food sources, achieving impressive diving depths. While they typically forage in shallower water, keeping their heads above the surface, they have the capacity for deeper dives. Observations suggest moose can dive as deep as 5.5 to 6 meters (18 to 20 feet) to reach plants on the lake bottom. These deeper plunges are usually shorter in duration.
The time a moose spends completely submerged is brief, but they can hold their breath for extended periods. Moose have been documented remaining underwater for up to 50 seconds while foraging. Some reports suggest they can hold their breath for a full minute, allowing them to graze extensively on aquatic plants before surfacing for air. They regulate buoyancy by expelling air from their lungs, which helps them descend and remain on the bottom while feeding.
Physical Adaptations for Aquatic Life
The moose’s ability to operate in water is supported by physical traits that contrast with its look on land. A specialized mechanism allows the moose to close its nostrils tightly when submerged, preventing water from entering the respiratory system during a dive. This closure is facilitated by fatty pads and muscles that respond to water pressure, a feature not seen in other deer species that do not feed underwater.
Their long legs, which look awkward on land, become powerful paddles when swimming or walking on the bottom. These limbs, combined with large, cloven hooves, propel the massive body through the water efficiently. The moose’s coat is composed of hollow guard hairs, which trap air that functions as insulation and significantly increases buoyancy. This natural flotation device, along with large lungs, helps the moose manage its position in the water.
Why Moose Dive
The primary reason moose dive is to access nutrient-dense aquatic vegetation otherwise unavailable to them. Plants like water lilies, pondweed, and milfoil provide essential minerals, particularly sodium, which may be lacking in their terrestrial diet. These submerged plants are also easier to digest than tough, woody terrestrial forage, making them a valuable food source during summer months.
Aquatic environments also serve as a thermoregulation strategy for these large animals, which are better adapted to cold climates. During summer, standing or submerging in cool water helps a moose prevent overheating and provides relief from biting insects like black flies. Water also offers a defensive advantage; a moose can use its swimming prowess to escape terrestrial predators such as wolves or bears, which are less effective in deep water.