Who killed the swimmer in the cave?

4 swimmers entered a round room with no windows and no doors, but there was a hole in the floor.

One man left through the hole in the floor and closed it behind him, but it is not how he arrived.

2 others were also found in the interior room, which had electricity and lighting, but a third was found dangling from his feet from the ceiling, with a puddle of water on the ceiling above him.

3 days later, the first swimmer was found floating face down in the hole in the floor, since it wasn't actually an exit, but actually an entrance to a system of caves with a lake inside it.

How did everyone actually enter the room, and who killed the swimmer in the cave?

• Wait... a puddle of water on/above the ceiling? Clearly gravity does not exist here ;) Feb 23 '19 at 23:07
• Are all the swimmers dead? Feb 23 '19 at 23:25
• @North I will leave that to your interpretation :) Feb 23 '19 at 23:40
• Let us continue this discussion in chat. (I'm removing my comments from your post now.) Feb 24 '19 at 19:43
• Has a correct answer been given? If so, please don't forget to $\color{green}{\checkmark \small\text{Accept}}$ it. If not, some responses to the answerers to help steer them in the right direction would be helpful.
– Rubio
Mar 7 '19 at 4:49

Expanding on other people's answers, I believe that the swimmers are

All fish in an aquarium with lighting. The first swimmer was sucked down into the filtration system of the aquarium, leading to him getting stuck in the small, filthy container typically located below the main tank. The two swimmers are minding their own business in the main tank area. The third swimmer is, sadly, dead, floating upside-down at the top of the tank.

I'm going to guess that they entered through

The mouth of a cave. Since a cave has a dome-like structure, thus giving it's "round" room. The mouth of a cave isn't exactly a door, simply an entrace (since a door requires...a door). The "hole" in the ground refers probably to a large lake of some sort and "closed it" when his body went submerged beneathe the water.

The person who killed the person in the cave is

The swimmer who found the room with electricty (?). Everything can be found naturally in a cave (the puddle on the ceiling refers to a stalactite, and light may be found through bioluminescent means or perhaps a light from a exposed ceiling) but electricty cannot be found underground unless through some man-made intervention.

The swimmers are

Excrement

They entered the room

via the digestion and excretion processes

The lake is

The water in the toilet bowl

and the puddle above the 'dangler' is

The digestive juices in a stomach

This is mostly a joke answer, but I don't have enough rep to comment; Can we get a hint? This riddle has been stumping me for a while.

• Oh my goodness this is my favourite answer. Line 4 could even refer to rot13(n pybttrq gbvyrg) Feb 27 '19 at 18:16
• +1 ah so the one that came back up was a floater Mar 1 '19 at 11:38

Don't yet have a full answer, but

I think that this must be related to a fishbowl or aquarium in some way. Fish turn upside down when they die, hence the odd perspective of the riddle (water on the ceiling, hole in the bottom.)

Will come back when I have a fuller answer.

• Haha I like it! Take my upvote ;) Feb 24 '19 at 15:16

My first thought is that this is some sort of:

Diving Bell or Submarine apparatus - On the surface some have a hatch (technically not a door) that you can enter through that you can't once it is submerged - hence the first man could have got in that way but left through the moon-pool style entrance.

But that fact that the bottom hole goes to an underground lake kind of blows that out of the water...

Also thought perhaps it could be:

a well

which would fit no windows / doors + water, and would link to an underground lake, but again there wouldn't be electricity etc...

My other whackier thought was that it was:

a toilet, connected to a septic tank and the 'swimmers' are fish

but there's no lighting involved there :-/ plus the fact you mention a 'man' specifically.

From the tags, I'm unsure if there's some cryptic crossword play going on here that I'm missing. It certainly looks like there's some metaphor-play here. I wonder if we need a few hints, pointers or clarifications to get any further.

4 swimmers are all human?

The 'man' who left through the hole in the floor is the 'first swimmer' that turns up dead and not someone separate from the '4 swimmers'

(presuming that doesn't give away part of the answer?)

Final thought:

Hydro electric generator?