COVE

This planet is the first planet in the system orbiting Gargantua.
It takes its name form the doctor who landed first on the planet.  It is also the first location for the crew of the Endurance visit.

Some informations: it's a waterworld, covered in a seemingly endless, shallow ocean.
The planet's gravity is described to be "punishing" at 130% of Earth's, forcing human astronauts to move slowly and with some difficulty while on its surface.
Time on this planet passes very slowly relative to the time experienced on Earth (a single hour on Miller's Planet would equate to seven years back on Earth).
That happens because of the planet's proximity to Gargantua: the immense gravity of the black hole causes the planet to be roiled by massive tidal waves as tall as 4,000 feet.
There is no sign of dry land on Miller, which may not exist because of the sheer volume of water on the planet.