Short and easy to ready, the submarine map does a great job of conveying setting while being a very functional navigational aid. Love the setting and the rising blood mechanic is a really clever way to increase tension and make things more desperate as the scenario proceeds. While it could use a bit more visual flair, it's a testament to the writing and mechanics that it manages to be so evocative with a relatively sparse layout.

Short, sweet, simple, effective, creative!
Although I'd like to see a longer and more fleshed out version, this is great!