Hranice, Czech Republic, hosts the world's deepest flooded cave

The Czech town of Hranice, located in the Moravian region, is home to the Hranice Abyss, recognized as the deepest known flooded cave in the world. The site is a significant destination for geological interest and tourism, particularly for visitors from neighboring Poland due to its proximity to the border.

In addition to the underwater cave system, Hranice offers historical attractions including a Renaissance palace with a glass courtyard, a historic synagogue, and a traditional town center. The area also features the Zbraslav Aragonite Caves in nearby Teplice nad Bečvou, which are celebrated for their unique formation involving mineral waters and carbon dioxide. To mark the upcoming centenary of the caves being opened to tourists in 2026, a special light installation titled ‘Pod hladinou’ (‘Under the surface’) is available through October.

Exploration of the Hranice Abyss has involved international cooperation, including work by Polish diver Krzysztof Starnawski, who utilized remotely operated underwater vehicles to study the flooded sections of the cave.