Room

From t2twiki

A room is a specific location, which may or may not be an actual "room"--many are mere roughly-defined outdoor spaces. Generally speaking, if you can see an item or another person without specifically looking into another room, you're in the same room as it. It is sometimes possible to be in the same room but at a different elevation relative to something else; flying creatures (including flying mounts) and the levitation spell are common examples of this.

Rooms all have descriptions, although rooms on the grid tend to use the same description over and over. Some rooms have actions specific to them. These actions may present a way of leaving the room, aside from the "obvious exits". If water exits are present you can swim away.

While in a boat, you are in a room, but the boat also functions as a room. Flying mounts are similar to this in some regards.