yes the developers made the map on Saigon higher then any other maps, like Operation Cedar Falls notice how the tunnel is in the hill. and the river around the whole thing is the almost the same height. but anyways you would need to (without raising the ground) would need to go the long way around. the Tunnel ends should start where the Hill flag is located under the wooden bridge; then go as deep as it can then go around to the Hill where the US spawns next to