What do convection currents do in the water?

Answer 1

A convection current is a cycle. The way the cycle works is when the liquid is heated the particles become less dense as it rises to the top and then it becomes more dense so it comes back down again. Then the process starts again.

Answer 2

Convection currents in the mantle act as a conduit for heat transfer from the Earth's interior, heat rising at mid-ocean ridges, hot spots, and rift valleys, and cooler material being drawn down at subduction zones at convergent plate margins.