Susan -- Between the German tourist and other campers (see Hero Camper Rescued Teens Fleeing Norway Massacre) campers on the mainland pulled "about 150 people from the water"; that's 25% of the number reported on the island and significantly reduced the target pool. It seems that getting off the island was a fairly successful tactic.

Teaching your children to swim well in open water would seem to be a good lesson to be learned; useful skill in any situation involving a lake, a river, the ocean, sailing, et al.

IMO charging the shooter would be a far less survivable tactic.