The Underwater Pen is an inventory item obtained in the main story in both Endless Ocean games. This item enables the player to suspend colored particles in the water, leaving marks as directions, temporary graffiti, or to unlock more information about creatures. The Pen uses five colours: red, yellow, green, blue, and white. There is not a way to unlock more pen colours. The marks made by the Underwater Pen only last for one dive, and they disappear whenever the player returns to the boat.