Your primary task, and what you're continually training for, is performing missions on the surface. It is hard, dangerous work, that takes a toll not only on the body but on the mind as well. You are part of a squad, and your squad eat, breathe, live and die together. Surface missions (what you call "topside trips") are usually only performed at night (when Enemy bio activity is lowest) and each squad usually perform at least one mission per night (led by MISCON crews).
Some of the more common types of surface missions include:
- Escort - Escorting and protecting foraging teams or science expeditions topside.
- Reconnaissance - Gathering intelligence on Enemy activity, observing movement or scouting out unraided loctions for scavenging expeditions.
- Tacops - Tactical operations is where you are actively looking to engage the Enemy in combat, most often in ambushes.
- Milk runs - Routine missions, usually following a set route to replace batteries in sensors etc.
Apart from mission ("mission time") SURFOPS teams also exercise and run tactical training scenarios.