Stockholm is a city built on 14 different islands connected by 57 bridges.

Stockholm's islands formed because of a process called post-glacial rebound. During the last Ice Age, heavy glaciers pressed down on the Earth's crust. This weight caused the land to sink. When the ice melted about 10,000 years ago, the land began to rise again.The ground in Stockholm still rises about 4 to 5 millimeters every year. This slow movement created the islands seen today. The city is located where freshwater from Lake Mälaren flows into the salty Baltic Sea. The lake surface is about 0.7 meters higher than the sea.Engineers built a lock system called Slussen to manage the water. This system stops saltwater from the sea from entering the freshwater lake. The 57 bridges allow cars and people to cross the water. Some bridges are short and made of stone, while others are over 600 meters long.The water around the islands is very clean. People can fish and swim right in the middle of the city. Stockholm is also the gateway to an archipelago of more than 24,000 smaller islands. Scientists track the rising land to see how the coastline changes over time.