|LEGO → System → Aquazone → Hydronauts|
6110 Solo Sub is the smallest Hydronauts set released. It is a small underwater vehicle piloted by a Hydronaut. The set has one propeller and no weaponry, but the Hydronaut has two attachments to its armor, which are both lights and possibly weaponry. The cockpit of the set is large enough to fit one Hydronaut, but the armor attachments must be removed to allow the Hydronaut to go inside. They are instead placed on top of the vehicle as weapons when removed from the Hydronaut.