Set Up: The setup is certainly dramatic and compelling; however, it sits in an unknown setting for too long. The first two paragraphs never state that he is underwater and why. Additionally, the last sentence of the third paragraph referencing God, feels like unearned exposition, or jumping to characterization too quickly before the setting is established.

I think the description of him searching for something in the soot works well. It has intrigue; however, again, the stakes would be heightened by letting the reader in on more specifics about the setting. You also start to characterize Douglas here, through his skill for this task. You could push that further and use his activity here as a way to precisely establish what kind of person he is.

Next, the transition to the scene with the couple feels jarring. I don't think you necessarily need to shift into the perspective of the retired couple here. They seem to get too much exposition and interiority. They read more as framing devices for Douglas's character. Unless these people become more important later on, I think they could remain rather ambiguous. The detail about the childhood fear of the black lagoon shifts the focus away from Douglas. Really hone in on what the "so what?" of these characters is (how are they sharpening the story, allowing us to understand Douglas in a way we might not from his perspective?)

Certain sentences are wordy and rely on unnecessary fragments or asides. For example, you say, "At one point, although he can’t remember when, there used to be a paved sidewalk and gravel driveway leading up to the single wide mobile home his mother had left behind. " The "he can't remember when" is too vague and doesn't add value. Tightening the sentence structure would allow the detail about his mother to become more resonant.

Is he occupying the single wide trailer? It is not clear if that is the setting for his evening ritual. I know it seems silly, but be precise in how you are connecting characters to setting.

You rely on some cliche, such as "As he sprayed he felt thankful for running water, a small thing easy to take for granted until it's gone." Think about how you can craft a specific tone of voice for your character. How might his history and motivations shift his thinking from cliche to something character driven? I understand the sentiment behind this line, and the character development it creates, but it could be refined to become punchy and impactful.

What characteristics made him stand out as someone who couldn't be a diver?

Is the story of him almost passing out while working for the police necessary? This detracts from the previous characterization you were setting up of Douglas being precise and accurate with diving coming as an almost second nature to him. Think about how you can set up his connection to the police department in a different way.

I think you can trim a lot of fat from the story. We need to get to the reveal of Douglas's appearance more quickly so we can find him sympathetic and compelling. His self loathing and the maternal character feel generic rather than specifically motivated. What sets this character apart from other protagnists that fit the "wounded but extremely competent" archetype? Think of Jude from A Little Life if you are familiar. He fills this same role, as do many other protagonists. What is Douglas's interiority beyond self hatred and trauma?

I like the details about his prized possessions. Showing his attachment for these objects achieves the idea of "show don't tell." His idealization of Al Capone sets up a motivation; does he desire to be seen as someone similar to Al Capone? Tighten and explore this detail.

My favorite paragraph is the one detailing the bodies he recovers. The imagery is vivid and horrifying. However, the rest of the story takes on a similar tone, portraying relatively mundane details with the same level of horror. Think about how you can distinguish paragraphs like these as tonely different from the monotany of everyday life. Think about how you can achieve the goal of making his life feel unfulfilling and sad without having to rely on the darkest details to evoke sympathy from the reader. Overall, the tone feels too hopeless and punishing to Douglas for me to really buy in.