Marine resources are essential for ecological balance.

The seaman has sailed on many seas.

The sailor sailed the seas for years.

San Marino is a small landlocked state in Italy.

He covered a thousand nautical miles during the race.

The submarine dives into the depths of the ocean.

The underwater is a fascinating technology.

The saltwater crocodile is the largest living reptile on Earth.

Scientists have discovered new species on the seabed.

This landlubber doesn't know how to navigate on the high seas.