When a person intentionally misses a regular obligation (such as work or school) and lies about his/her whereabouts. The term scuba refers to the fact that the person will have been in a warm climate where scuba diving is possible (e.g. the Caribbean).
Person 1: Hey, where's Bob he hasn't been in to the office for quite some time.
Person 2: Well, he texted me yesterday saying that he was sick but personally I think that he's Scuba Skyving