Eelgrass is widely distributed in temperate and cold waters of the Pacific and North Atlantic. It is most common in shallow waters, sometimes exposed at low tide, but has been found at depths of up to 100 ft.

Seagrasses can grow into thick, luxuriant beds, which often consist of more than species of seagrass and many species of seaweeds. Seagrass beds rank among the most productive communities in the entire ocean. The dense seagrasses also offer shelter to many animals.