Mercury is a hot, airless, metal rich planet and the closest to the star Sol. While not the hottest planet in the Sol system, it experiences the greatest temperature variation out of all the planets due to its lack of an atmosphere. On the star-facing side of Mercury, temperatures can reach a searing 801° Fahrenheit, hot enough to melt lead, while on the dark side it can reach a frigid -279° F, cold enough to turn a human being into a living ice cube.
Metal rich worlds like this have a large metallic core, with plentiful metallic ores even at the surface. In places, especially around areas past or current volcanism or liquid erosion, some higher metals can be found in their elemental form too. Mining is therefore very efficient, so these worlds are highly valued.
— In-Game Description
It has no atmosphere, so can be landed on in Elite Dangerous: Horizons. There are 3 surface ports on the planet's surface: