Right, many of you have probably noticed that Foxtrot has a weird ladder under it. If you start breaking the concrete walls on the side of the base of the sattelite at 3:33, you can enter. Once inside there is a ladder that leads to a chamber of concrete, breaking the floor opens up a watery pit with 2 altars at the bottom. I haven't gotten further than this, the only thing you need is the Scuba Gear to descend but anything beyond that is a mystery to me. Any ideas?