Iceland has the Þingvellir valley, which is an above-sea continuation of the rift valley down the middle of the Mid-Atlantic ridge. It includes the Silfra, which is underwater (fresh water) at the lowest part of the valley. The Great Crack in Hawai'i is of course not such a major rift, but it is the same idea: upwelling magma raises the ground, creating a crack like in a loaf of raising bread.
The Great Rift in Idaho is another volcanic rift valley, which (IIUC) passes through Craters of the Moon National Monument (where the Apollo astronauts trained).
The Great Rift in Idaho is another volcanic rift valley, which (IIUC) passes through Craters of the Moon National Monument (where the Apollo astronauts trained).