"PENALTY STROKE - an additional stroke which is added to a golfers score for a rules violation, going out of bounds, losing a ball, or various other situations." Source
It looks to me as if the diver was taking way too much time looking for the golfer's ball, which had landed in the water. The golfer, not wanting to waste anymore time, says, "Maybe I should [just] take the penalty stroke [instead of wasting time standing here, waiting for you to find my ball]."
Student or Learner