my opinion - just to be sure my wizard would use a potion to survive underwater (although as GM i think magic that is cast on land, transforms the body and then going into the water should work just fine). he has several mixtures for this. one transforms the drinker into the creature from the black lagoon movie, with aquatic and a host of other powers, costing a lot of fate points (useful to salvage depleting uranium from sunken submarines). another potion simply enhances endurance under water with it's strength, allowing the char to hold his breath "very long".
my character also has a pick lock rote, but he uses earth/magentism for this.