Watery Grave is the sequel to Watery Death, a map that made many Arena players fear splash damage in ways that one would never imagine.
You know how this works: your equipment is given to you upon spawn via your favorites. You cannot use any armor besides the default Light. Shoot the center of any of the 64 tiles, and it will disappear for a few seconds. Anyone can fall into the gap created by the disappearing platforms, and fall to their doom - to which you get credit for the kill!
In Deathmatch, you launch into the air upon respawn.