Sea of Tranquility: Location on the Moon

Mare Tranquillitatis (Sea of Tranquility) is a lunar mare (basaltic plain) on Earth's Moon.

• Location: Northeastern quadrant of the near side (Earth-facing hemisphere).
• Coordinates: ~8.5° N, 31.4° E.
• Diameter: ~873 km (542 mi).
• Geology: Formed by a giant impact basin ~3.9 billion years ago, later flooded by low-viscosity basaltic lava that smoothed the floor.
• Famous for: Apollo 11 landing site (July 20, 1969) — "Tranquility Base" at 0.674° N, 23.473° E, near the southwestern edge.

It appears as a large, dark, relatively smooth patch on the Moon's face—visible to naked eye from Earth.