An axolotl can live above water, despite the fact that they are usually kept in aquariums. If they travel beyond the surface, they will simply drop their gills and use their lungs instead. Once an axolotl has gone onshore, they start mutating and this mutation is completely random. They can never return to the water again, or they will drown.
After their mutation, a grounded axolotl's lifespan is shortened from 10-15 years (though the oldest ever axolotl was 25 and lived in Paris) to a maximum of 5 years and most commonly only a few months.

As a bonus info, I can inform yo that I breed axolotls.