Seas Mare Ingenii Origin of the name "Sea of Cleverness." When to observe it On the far side: it never faces the Earth. Only spacecraft have seen it. Nearby Thomson 42 km Zelinskiy 147 km Obruchev 175 km O'Day 212 km Birkeland 255 km Van de Graaff 266 km Oresme 303 km Seidel 315 km