Mühlendammschleuse, Navigation lock at Rolandufer, Berlin-Mitte, Germany.

The Mühlendammschleuse is a double chamber lock on the Spree that equalizes water between two different levels and allows ships to navigate through Berlin. The system consists of two adjacent chambers working sequentially to move boats both upstream and downstream.

A wooden lock was built in 1578 in the Cölln city moat, a side arm of the Spree, and was later called the Stadtschleuse. It was repeatedly enlarged until 1885, when it was last expanded and already seen as a bottleneck. The current Mühlendammschleuse replaced it in 1894 as a single-chamber lock, making the main arm of the Spree navigable; from 1936 it was rebuilt as a two-chamber lock and opened in 1942.

This lock shows Berlin's role as a port city and water transport hub in the heart of Europe. The passage between the chambers reveals the everyday rhythm of boat traffic as vessels from different directions wait their turn to pass through.

The lock is visible from nearby banks and is best observed during daytime when boat traffic is most active. A leisurely walk along the riverbank offers good views of the chambers and helps you understand how the system works.

The lock is a key meeting point for different types of boats, from cargo ships to private vessels, all using the same system. This variety makes each passage an interesting spectacle where you can watch different craft and their crews.