Find 815 clues/January 11

I think I have made a big mistake. At the moment, we're about 300 km off the Indonesian coast in an area called the Sunda Trench. Deep waters around 7,000m in some parts. And sure enough, the Christiane I's mission is to search for a sunken slave trading ship called the Black Rock that disappeared in 1881 whilst returning from a gold mining expedition around Papua New Guinea. I mean, that's all very exciting, but what does it have to do with 815? I'm starting to wonder what the hell I'm doing here. I thought following this lead would give me something to do besides just sit around and think, but sailing up and down over miles and miles of ocean looking for a needle in a hay stack 7,000m deep unfortunately gives you nothing but time to think. And what else makes wonder whether this is all worth it is... I received another email. This Maxwell Group, I just don't know what to make of it. It's just incomprehensible numbers. I can't make any sense of it no matter how long I stare at it. Maybe I just, I don't know, read too much into the first email. It's just somebody having a laugh because they saw me mouthing off on TV. Well, some joke. Now I think I'll just get off at next port. There's nothing to find out here.