I'm fairly certain that BUD/S doesn't cover diving to the depths of those pipelines. Initial SEAL dive training is focused on open circuit compressed air and oxygen rebreather equipment. Deep, covert demolition missions like this would likely have to be done on a Mk16, and most SEALs lack that specialized training. I doubt the US Navy actually sabotaged those pipelines, but if they did then the diving was more likely handled by EOD or MDSU personnel.