The sinkholes of Argostoli are a popular tourist destination and are a very unique natural occurrence. These natural formations, known as katavothres, are formed when underground water erodes the limestone rock, creating deep, vertical shafts. Visitors usually watch the sinkholes from a viewing platform; some even brave the descent into the sinkholes for a thrilling experience.
The sinkholes are an important part of the island's ecosystem, as they help to recharge the groundwater supply. So tourists who are also interested in geological phenomena will find these sinkholes interesting and enjoy it a lot.