The Inland Sea is a cliff-bound lagoon connected to the open sea by a tunnel that runs for 100m through the headland of Dwejra Point. The tunnel is big enough for small boats to sail through in calm weather, and the Inland Sea has been used as a fishermen's haven for centuries. Today, fishermen supplement their income by taking tourists on boat trips through the tunnel. Trips pass over the remains of the Azure Window in the crystalline waters.