Mergansers stopped on the pond for a rest. They floated in the early sunlight for a while, then dived under water to search for a meal. Maybe they found aquatic insects, worms, frogs, or snails.
Below, the duck on the right is just gathering her body upward to curve down and dive. Because feathers make ducks buoyant, it takes muscles to dive. The one on the left is just emerging from a dive, as the water rolls off her head.
