Making progress through the water; not at anchor, aground, or made fast to the shore

currently in progress; "there is mischief afoot"; "plans are afoot"; "preparations for the trial are underway"

The condition of a vessel not at anchor and not made fast to the shoe or aground.

The trip, alas, has begun.

A ship in motion. Once your ship has left the pier or its anchorage, the ship is considered "underway."

When the ship is about to depart

The act of sailing

moving under power of sail or motor.

Moving, at last.