Few sights underwater are as mesmerizing as a field of garden eels swaying across a sandy seabed. At first glance, they resemble a patch of eelgrass—until you drift closer and watch the shy creatures slip back into their burrows. Living in colonies that can number in the thousands, garden eels spend their lives anchored in the sand, emerging to feed on passing zooplankton. They inhabit sandy bottoms throughout the Indo-Pacific and can reach lengths of up to 120 cm (4 ft).

Photo tip: Rest your camera on the seabed and swim away, giving the eels time to reappear. Return after about four minutes to capture truly captivating footage.