Exactly, in fact in the British Isles even the land above the high tide line (I forget the exact extent) is public. In New England they wanted to encourage the development of docks (to promote more commerce) and extended ownership to include the land on which docks would be built.
"1647 Colonial Ordinance enacted by the Massachusetts Bay Colony ceded title to all intertidal land in what would become the state of Massachusetts to upland owners to encourage “wharfing out” (marine commerce)."
