Why prisoners on sunk Japanese ships were difficult to rescue

How often were Allied prisoners rescued from Japanese ships after those ships were sunk?

Rescuers helped when they could, but submarines and aircraft often sank the transports without a surface force remaining nearby to recover survivors.

A surface action could leave friendly ships close enough to recover survivors. Submarines and aircraft operated under different constraints and often could not remain alongside a sinking transport. Many prisoner-carrying ships were therefore lost in circumstances where no practical rescue force was present. Weapon platform and tactical situation shaped the chance of survival after a sinking.