The Tuna Hästberg mining field, which is 47 hectares in size, consists of the Rämpsgruvan, Vattugruvan, Kärrgruvan, Hinsgruvan, and Strimsgruvan outcrops with the iron ore lying in a strip in an east-west direction. Down in the ground, the strip runs at a 30-45 degree slope and flattens out at the deeper levels.

Ore was already mined in Tuna Hästberg during the Middle Ages, but it was not until the mining was modernized at the beginning of the 20th century and communications were improved around the mining to transport the ore that significant mining could be carried out in the area.

For a long time, the 120 m level in the mine was the lowest level as it was not considered profitable to go deeper due to the lower proportion of iron in the ore. Despite this, people went deeper into the rock in the hope of finding more iron-rich ore, which they did, and the mine was expanded down to 360 m. Diamond drilling down to 590 m has been carried out and shows that it is likely that there is a lot of iron-rich ore left to be mined, as Domnarvets Järnverks hytta, which was the only recipient of the ore from Tuna Hästberg, closed down its operations to switch to the production of special steel. Mining operations in Tuna Hästberg were closed down on 30 June 1968.

Today, all open pits are fenced off to prevent people and animals from falling into the holes in the ground. The rock is relatively stable and no major landslides have occurred, and due to the strength of the rock and the fact that shafts and pits on all levels of the mine were in good condition at the time of closure, this indicates that the site is relatively safe from a landslide point of view.

There are several entrances that you can use to enter the mine, but through the manhole, which is about 5 m wide and 3 m high and goes down a slope of about 45 degrees into the rock, it is quite easy to get down into the mine. The mine is dry down to the level of 80 m. The water surface then starts at about 85 m and there are lots of places you can start from when you do your dives. The visibility in the water is very clear and there are lots of things to look at.