Infinite Tunnels in First Level?

In the first level, which is also a sort of tutorial, there is a grate that you can break open and crouch to walk inside of, right after you take the elevator up.

This tunnel takes you a few places and at one point it seems like a dead end and the only way to go is to drop a long way. You land in water and there is a ladder that takes you to these tunnels that just keep going, seemingly forever. they all look like this screenshot and when you get to the end of one there is a left or right bend and then it is another identical tunnel.

Are these tunnels infinite? Or do they lead somewhere?