So What Made Underwater Levels Suck?
I don't know if people agree with my opinion here but personally, water levels felt slow and maneuvering felt everything but precise. Having an air system that may run out made it all even worse. I understand that these mechanics are supposed to be like that. Have you ever walked next to someone swimming? Guess what? you're walking faster than they're swimming. Have you noticed that the Zora transformation in The Legend of Zelda: Majora's Mask lets you swim much faster? Or the frog suit in Super Mario Brothers 3? Have you tried to stay underwater for longer than five minutes? (I hope not...)
From a game design perspective that's fine. Nothing to complain here.
Enough About Other Games
Anyways enough about other games. The problem we want to focus on is the underwater in Guild Wars 2. So what is it that makes the underwater fighting so lame in Guild Wars 2? Well, several aspects.
Areas of Effect
Above ground, underground or wherever but not in the water, you can place AoEs and enemies place AoEs. Aside from all the effects and everything flying around you can see all the damage fields you have to avoid or look at the precaution or warnings shown before some attack comes. How are you supposed to show these underwater? How are you supposed to see the effects of swimming around next to you?
Additionally, placement skills can't be placed in the middle of the water. You can either place them on you or on the enemy. How fair is that depending on the skills?
Abilities Underwater
Compared to on the ground, underwater disables several of your abilities. Okay, it makes sense that a few skills do not match underwater fighting. Can you imagine swimming flower turrets, a drowning flesh golem or something like that? I can't. Unfortunately, some elite specializations like the scourge have all their new learned skills disabled underwater and it gets even worse with
Weapon-Based Traits
"Your scepter now does more condition duration", "Your greatsword heals" etc. etc.
Notice something? Let's check my weapons underwater... hmmm.. none of those. Yeah, this kinda makes the traits completely useless. They have no effect underwater. None at all. So There's no reason to take these traits with you, however, there isn't a better option to compensate for the missing ones. This is a huge problem with dealing damage underwater lowering the damage of players and lower damage means longer fights which then means it gets boring or annoying.
My Suggestions
I already mentioned before I don't like to criticize without giving suggestions and well... sometimes it's hard to find one. In the case of area of effects underwater I'm kinda left in the dark, unfortunately. Of course, you could mark the area with a red bubble or an orange bubble that fills or something. At the same time, this might decrease how well you can see things. You could make it opaque... but I don't know about that. I guess you could try going for opaque.
To the rest of the problems, one solution could be to add elite specializations for underwater fighting. Unfortunately, you would have to change your build every time you go underwater or alternatively add an "underwater" build like the distinction between PvE, PvP and WvWs builds. The other solution could be to change the skills to work underwater. Like the flesh golem of the necromancer becomes a flesh shark - currently thinking about the Pirates of the Caribbean's ghost sharks. The traits could be changed to implement the underwater skills and weapons in them raising underwater damage onto the same level as on the ground.
In The End, It's All Opinions
I think a lot of people agree that underwater fights don't feel "right". The suggestions I posted here depend on my own opinions. Someone else might disagree, but it would be cool if we find a way to agree with something that improves the underwater fighting to feel much better and allow us to enjoy this content of Guild Wars 2 as well.
Besides, I think we all agree that fighting the dragon S... on some planks on the open sea sounds ridiculous.
BONUS CONTENT
Another aspect I didn't wanna mention is underwater PvP. Before the only water map was removed from the rotation and re-implemented without water there was an Elementalist bug that allowed him to infinitely go into downstate mist form when a top of water. Even worse is the aspect that back in those days there was no stomping underwater, which means ranger were nearly invincible in downstate while the pet was reviving.