1- Hostage holdup animation
2- C-130 Skyhook pickup system or variant with script to execute towing in of the balloon and the hoist.
3- Silent Hunter 5 styled water effects on goggles, specially with Navy Divers.
4- Conducting underwater harpooning of enemy divers, maybe acquire their oxygen tanks, or masks.. (too much for the crew I know, bear with me).
5- underwater sunken vessels, maybe WW2 submarines, or merchant men (handelschiffe)