I have a feeling this is lake Powell USA. Certain parts of the lake are very difficult for people to reach and take hours of travel. There are many local drives nearby that own the reservations the lake sits between. I don't know a ton about the local lore, unfortunately, all I know is what I've experienced firsthand.
7 years ago I went to this lake with my boyfriend's family at the time. Him, and his father, we're both experienced divers, and often dove to the bottom of the lake by camping/house boat destinations to find "treasure". (Whatever happened to fall off the back of boats and jetskiis. Namely sunglasses, towels, rings, diving gear etc) I'd wait dutifully by, checking the neon orange and yellow bobbers now and again, for signs of distress or surfacing.
I finally noticed the bubbles, around the closest bobber to myself, in my periferal. I was relieved they were finally coming up (it'd been at least a half hour by now), and set my book aside to greet them from the shore. I remember stretching a little, even lazily yawning before I realized... the other bobber was gone. I stayed calm, thinking I must have dozed off, and waited for the bubbles to get bigger and more rapid. I prayed it was my bf. His dad was a bit intimidating, and he was always doing crazy things that would end up killing him someday...
After 15 minutes, I saw his dad's pepper colored hair rise above the soft waves... and I immediately became afraid. I asked him if he'd seen his son recently. The last time was about 20 mins before, but "he had less O2 in his tank, so he should have come up sooner..." I ran to the wave runner, and booked it to the center of our cove. If he had run out of rope, and dragged his bobber under the surface (difficult to do without noticing, but I wouldn't have put it past him), it would have to have been pretty deep. Once in the center, around where I thought I'd seen him last, I tied my line to my wave runner and dove. I'm a decent swimmer, once I even trained to be a professional mermaid (it's a thing), but I could hold my breath at this point for just shy of 4 minutes. I dove as far as I could still see with goggles. The floor of the lake had roughly 10 feet of silt and mud at the bottom, and in the murky water above that, you could still see only about 6-7 feet around yourself. I saw an underwater beaut close by, that stood just taller than the silt and swam that direction. I breached for air, and noticed how huge this under water surface was. Could have been a decent beach if the tide was low. I was so sure he'd be close by, as places like these tend to be where we'd find the most things.
I dove down to just about 10 feet from the surface of the beaut, and swam parallel to it, towards the center, in a spiral from the outside. After surfacing a couple more times, the panick began to set in. If he wasn't here, I wouldn't know where to look. Everytime I surfaced, I'd check with his dad (or mom, who'd joined the search by now) and 15 mins later, still we had nothing. I was about to go back to the boat, but a crazy sense of spiritual heaviness hit me. I dove once more and once I'd gotten to the center of the beaut, I suddenly felt eirily calm. I felt my body relax, even as my mind raced. I was suddenly prepared to act, even floating, suspended in the murky brown and green water. The lakes plant life, winding it's tendrils around my extremities, I finally became conscious to another presence. This figure was grotesque, and non human. But it didn't strike me as a danger in that moment. Thinking back, it should have terrified me. It was organic and dark, like a clump of lake weed, but it moved with an almost crazed rhythm. The bits of it that seem human would only show in flashes of white and grey, through the cracks in its living garments... I didn't realize until I saw my bf, but I'd been following this creature. When the visual of my bfs lifeless body sunk in, I thought of nothing else.
This all took place so quickly, it's easy to get lost in my own thoughts about it. I managed to drag my bf to the surface, after slicing the rope from the submerged tree he'd gotten tangled in. It wasnt until I was on the boat, practically sobbing, and still panting from exertion and adrenaline, and he'd started hacking up a lung, that I really even thought about that thing again. Mostly just because my bf was okay, but also wondering if I had given myself the bends. I didn't think I'd been diving that deep, but I still don't know. For obvious reasons, ops story made me think of this again (it's been 7 years, and I've only ever told my bf at the time, and my therapist). My bf said I was just making shit up, and saving his life didn't give me too many points, coz he dumped me pretty shortly after.
I don't know what helped me find him that day, but I'm more greatfull than anything. I would have been a completely shattered person if I'd only discovered a corpse by the time I'd have found him on my own. I don't remember exactly which cove, but it was around 2 hours of speed boat ride from Bullfrog.