Velsen (population: 66,798) is a municipality in the north-western Netherlands, in the province of North Holland, on both sides of the North Sea Canal. It covers an area of 52.87 km² (of which 6.30 km² water).
The municipality of Velsen comprises the following towns, villages and townships:
- on the north of the North Sea Canal:
- Velsen North, with Hoogovens, the Dutch division of Corus, on the west and a residential quarter on the east
- on the south of the North Sea Canal:
- Velsen South, Driehuis, IJmuiden, Santpoort-Noord, Santpoort-Zuid and Velserbroek.
There are the following connections across the canal:
- A railroad tunnel between train stations Driehuis and Beverwijk.
- Road tunnels, from east to west:
- Wijker Tunnel
- Velser Tunnel next to the railroad tunnel
- A ferry .
Also there is the Fast Flying Ferry to Amsterdam 
The Kennemerstrand beach on the nouth side of the canal is at the end of the Kennemerboulevard, which runs south of the Seaport Marina.
To the south is the beach of Bloemendaal aan Zee. In between is a nudist beach (see ).