what is the floating thing in the hot tub

It’s likely a hot tub boat or other floating hot-tub attraction, not a random object in the water. Recent reports describe rentable floating hot tubs on the Mississippi River in Minneapolis, including built-in electric tubs that can carry up to six people.

What it probably is

• A small boat fitted with a hot tub.
• A novelty rental for sightseeing or relaxing on the water.
• Usually operated as an organized attraction rather than a personal tub drifting away.

Why people notice it

These floating tubs are visually unusual, so they tend to go viral when they appear on rivers or lakes. Coverage this year notes they’ve been drawing attention in Minneapolis and are booked as 90-minute rentals.

If you meant a loose object

If you were asking about something floating inside an actual hot tub, it could be body oils, debris, calcium flakes, or residue from the tub itself, depending on what it looks like.

In short: most likely a floating hot tub boat.