I have my line run through a 3" pvc line that comes up through the floor of one of my buildings. The compressor is in the building and the pvc is large enough to pull additional lines through if needed. The pvc comes out in about 3 feet of water but could be continued. I pass it through concrete blocks to keep it in place. This would be difficult for deeper depths but the large coils of black water line could also be used. I use them for electrical wire I use underwater or bury as an extra proctection from abrasions. A 100 foot roll is 20-30 bucks at menards.