Maybe its something like Hibernation(I think).
because my turtle 1 year ago when it was very young, it was in the water for almost 2 days (it was under a tree bark and it had eyes:whiteish)
Reptiles do not hibernate but actually brumate
, becoming less active but occasionally rising for food or water. Brumation can occur in varying degrees. Red-eared sliders brumate over the winter at the bottom of ponds
or shallow lakes
and they become inactive, generally, in October, when temperatures fall below 50 °F (10 °C). Individuals usually brumate
underwater. They have also been found under banks and hollow stumps and rocks. In warmer winter climates they can become active and come to the surface for basking. When the temperature
begins to drop again, however, they will quickly return to a brumation state. Sliders will generally come up for food in early March to as late as the end of April. Red-eared sliders kept captive indoors should not hibernate. To prevent attempted hibernation/brumation in an aquarium, lights should be on for 12–14 hours per day and the water temperature should be maintained between 76–80 °F (24–27 °C). Water temperatures must be under 55 °F (13 °C) in order for aquatic turtles to brumate properly.
I'm not sure if the problem related to your turtle is the same here(because it is just a baby)
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