Leeloo is a pretty smart cracker. Sometimes though, she is foiled by sheer physics. The ocean water here is clear, almost crystal clear. So when she is in the water she can see things that are under water very clearly and, being Leeloo, she wants them. Not to eat (usually), just to investigate. But how, pray tell, does a Leeloo investigate something that is under a foot of water? Well, she doesn't. Mostly because that would involve putting her nose into the water and thus the issue comes to light.
Normally, if you paw at whatever is covering the thing you want you can move the obstacle and retrieve said item. However, water is not Leeloo's friend. It stubbornly refuses to get out of her way no matter how hard she tries. At this point I think it's just the principle of the thing but as of 4pm last Sunday water is still the undefeated champion. So, for now and forever more that shell/rock/seaweed will remain untouched by Leeloo lips. That is unless she gets up the courage to stick her nose under water. So ... never.