How do u get past the waterway 2 level.

I can't remember what level ur talking about but...
There will always be another way out, check the levels, there may be a platform above you, switches are obvious things often red or green and are activated by pressing square, double check you haven't missed a door or a ladder.
New guards mean new places, you may have to get to a ceratin point before a door opens and a load men run out of it.

I hope this helps.