What kind of thermodynamic process is an air bubble rising to the water surface?

[corona7w]

There is an air bubble at a certain depth and it's rising to the surface of the water. The temperature of the water is constant at a certain temperature. The gas inside the bubble expands as it rises to the surface, but does the temperature of the air stay the same? Is this an isothermal or adiabatic expansion?

 

[corona7w]

I just heard from someone that is the bubble rises infinitely slow to the surface, then the process is isothermal because it doesn't have time to exchange heat with the water surrounding it in order to maintain a constant temperature within. But in real life, in which air bubbles rise quickly to the water surface, the process would be adiabatic. Can this argument be established?