The drop from the ice surface to the water surface of the abyss was nearly one hundred meters, and the sub-zero temperature of almost -200 degrees Celsius rose sharply below the depths, almost reaching 10 degrees Celsius.
According to a good explanation from human geology, as long as the planet's core is not completely dormant, it will continuously emit heat, either in the form of underwater volcanoes, allowing the bottommost water molecules to remain liquid by relying on this heat and forming an ocean beneath the ice surface.
The closer to the bottom, the higher the temperature, which might provide a warm environment suitable for microbial life, synthesizing the majority of organic matter.
It is on this basis that people can speculate that Titan may harbor life—there is water, temperature, and organic matter, at least there is some hope near underwater volcanoes.