The spell Life Bubble says that the creature obtains a moveable shell, which means that it can be moved, but then says you cannot move on conditions that impede movement (such as being underwater...):
You surround the touched creatures with a constant and moveable 1-inch shell of tolerable living conditions. (...)
Life bubble does not provide (...) ability to move or act normally in conditions that impede movement (such as underwater).
However, neither the rules for Swim or the rules for Aquatic Terrain say that a character cannot move underwater. The only exception being if they fail their Swim check, otherwise they can move 1/2 or 1/4 their land speed.
Characters need a way to breathe if they’re underwater; failing that, they risk drowning. When underwater, characters can move in any direction.
The exception on the spell's text should still apply, but that example was terrible and (in my opinion) poorly written. What it actually means is that it does not grant you a movement speed on that enviroment.
For underwater movement, that being a swim speed.
Can a fish move out of water?
This is a question that treads on murky waters. But long story short: The rules are unclear.
There are no rule saying that you cannot move on a surface where you do not have a listed speed, there are rules saying you cannot take certain movement actions if your movement is hampered, or that you cannot take 5-foot steps on speeds you do not have, or that you cannot take certain movement actions on speeds you do not have.
However, there is a rule saying that you can move at least 5 feet in any direction regarless of movement penalties you have using a full-round action.
Despite whatever penalties to movement you might have, you can take a full-round action to move 5 feet (1 square) in any direction, even diagonally. This rule doesn't allow you to move through impassable terrain or to move when all movement is prohibited. Such movement provokes attacks of opportunity as normal (despite the distance covered, this move isn't a 5-foot step).
The part that says "to move when all movement is prohibited" is the key here. And there is nothing saying that a creature with only swim speed or without legs cannot move on land. So this exception only applies if the creature has any condition that says that they cannot move.
But the opposite is also true, a listed speed is what allows you to move on certain enviroments. If you do not have a listed speed, your speed is 0. But how this interacts with the rule i quoted above is left at GM's discretion.
This rule is normally applied on difficult terrain and conditions that reduce your speed. But it is also applied even if a condition should reduce your speed to 0 due to penalties, since certain conditions reduce your speed by a fixed amount instead of a fraction of the base value.
Since the rule for moving on an unlisted terrain is missing, we also do not know the proper behavior of Expeditious Retreat or Animal Aspect (Raptor) on a Shark.
How to walk on land?
One thing is certain, the spell Fins to Feet (1 hour/level duration) should definitely fix this problem, as it replaces your swim speed with a land speed of 30 feet.