In places where the temperature changes across seasons, winter is the coldest part of the year. During winter, many animals greatly reduce their activity, often finding burrows or other retreats to stay in until spring. However, these retreats are not usually the same retreats in which they were born or hatched.
One exception is turtles. Some adult turtles wait out the cold of winter under water in ponds or lakes that may freeze over. Overwintering under water can be a problem for young turtles, because it is hard for them to deal with the very low levels of oxygen (water is <1% oxygen, while air is ~21% oxygen). So, if overwintering underwater would not work, where can hatchlings safely spend the winter? In burrows, underground. But there is one more problem. Turtle embryos are not very resistant to freezing. If it gets too cold, embryos still within eggs could die, while hatchlings have a better chance of surviving. For the best chance of survival, some baby turtles hatch from their eggs (so they would not freeze) and wait in their nests (to get enough oxygen) until spring, when the weather warms and they emerge .

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Go to source: https://kids.frontiersin.org/article/10.3389/frym.2019.00017