Ryan got curious about the subject, so he asked a little more about the Hydras to Gustavo. According to him, they were essentially invincible in the ocean. While they could be wounded, they could heal insanely fast. Gustavo and his friends didn't even have the chance to try to behead one and see what would happen. So, they were unaware if those creatures could obtain two more heads when they lose one.
Before he could notice, Ryan created a massive pool and then entered it to train his Underwater Resistance. While that was beyond unpleasant, Ryan discovered that he could increase his time underwater by using Regeneration and other healing spells. Thanks to his health, Ryan could stay for quite a while underwater, but losing health for being unable to breathe was, again, beyond unpleasant.