In Celtic lore, the god known as the god of the sea is Manannán mac Lir. He is often depicted as a powerful and benevolent deity who governs the seas and the mysteries associated with them. Manannán is known for his magical abilities, including the power to create illusions and to control weather and tides. He serves as a protector of sailors and represents the relationship between land and sea, embodying the fluid and unpredictable nature of the ocean.