The IJmuiden Sea Lock, opened in 2022, is the largest sea lock in the world: 500 metres long and 70 metres wide, capable of handling the biggest vessels afloat. It sits at the point where the North Sea Canal meets the North Sea, and watching an enormous container ship or bulk carrier pass through the lock chamber is one of the more extraordinary industrial spectacles the Netherlands offers.
The lock complex is visible from the surrounding embankments, and there are viewing areas along the canal-side where you can watch vessels transit. The new lock replaced the 1929 North Lock, which was itself the largest in the world for decades. The older locks — now mostly used for smaller vessels and pleasure craft — remain alongside the new structure and give a sense of how the engineering scale has grown across 150 years.
The North Sea Canal runs 25 kilometres from this point to Amsterdam, and the lock system maintains the water levels that protect much of the western Netherlands from flooding. It is, in that sense, not just an impressive piece of civil engineering but a critical piece of national infrastructure.