Diving in Rummu Quarry, Estonia 2025

Diving in a prison. Seems rather weird, but it's a real attraction in Rummu

Best time: May–September

A former Soviet prison in Estonia has now become a diving attraction. Established in the 1940s, it was used as a quarry for Vasalemma marble with prisoner labour. When Estonia became independent, the labour prison in Rummu fell and a quarry was closed. Thus natural ground water flooded the quarry and the prison so fast that all the machinery and buildings ended up underwater. Now this place looks like a blue lagoon.

The Rummu underwater prison is a very popular tourist destination and diving spot. Locals usually come here to swim in summer. The water is clearer in autumn, so it's best to dive here at this time. There is one thing you should know that it is an unofficial and unguarded place for swimming or diving. Diving can be dangerous if you don't know what is waiting for you. Guided tours can be a safer option.

Practical info

When is the best time to go diving at Rummu Quarry?

The ideal time for diving at Rummu Quarry would be between May and September, as the water temperature is considerably warmer and the climate is milder. Diving during autumn offers clear water, but winter is best avoided due to the icy temperature, which can be a danger even to experienced divers.

Are visitors allowed to swim at the flooded Rummu Quarry throughout the year?

Yes, visitors, are permitted to swim or dive in the flooded Rummu Quarry at any time of the year. It is an unofficial and unguarded site, so tourists can visit anytime they wish. However, visitors should be aware of the unstable infrastructure and deep waters, making it difficult to navigate alone. Opting for a guided tour is recommended to ensure a safer experience for all.

Is diving at the flooded Rummu Quarry safe without a guide?

The flooded Rummu Quarry holds dangers to divers and swimmers, making it unsafe to dive without a guide. The site has deep waters and unstable infrastructure, which could lead to accidents or injuries. Experienced divers may find it challenging, and inexperienced divers should stay away. It would be best to take guided tours, which provide an extra layer of safety while diving or swimming at Rummu Quarry.

What are the underwater features to witness while diving at Rummu Quarry?

While diving at Rummu Quarry, visitors may not find unique marine species, given that the water is relatively shallow, with a depth not exceeding 22 meters. Divers may observe submerged buildings that belonged to the prison and parts of the old machinery used for mining operations. The site is popular for its crystal-clear water and the surreal and eerie feeling that comes with discovering the surroundings. Diving or swimming in Rummu Quarry offers a one-of-a-kind experience unlike any other location.

What is the history behind the site of Rummu Quarry?

Established in the 1940s as a labour prison for mining Vasalemma marble, Rummu was later abandoned following the country's independence from the Soviet Union. The result was the flooding of the site by natural groundwater. Today, Rummu Quarry is a popular unofficial tourist attraction and diving spot with remains of the old mining machinery and buildings that belonged to the prison which now present an eerie underwater landscape. The site is comparable to a blue lagoon, taking its visitors on a surreal journey to a bygone era.