A tomb (from Greek : τύμβος tumbos )  is a repository for the remains of the dead. It is generally any structurally enclosed interment space or burial chamber, of varying sizes.
There are seven optional Tombs in Tomb Raider. Completing them all will net the following award, as well as a Treasure Map (or partial treasure map) for an area on the island. An "8th" tomb, available as DLC and included in the Definitive Edition ( Tomb of the Lost Adventurer ), does not count towards the achievement condition.