Underwater karaoke [Skill/feat/advantage]

I saw a dream, where I kinda played this roleplaying game, kinda wrote it. Not sure, but sometimes dreams can be a bit blurry in detail. But this game was Dungeons & Dragons but with Storytelling system. And there was a skill called Underwater Karaoke (or I was writing it). Sounds strange? Not necessarily. Well, the name is a bit strange...

Underwater Karaoke


Underwater karaoke is character's skill or quality, where he is as good performing underwater as he is on solid ground. So there are no penalties to his action. Name "underwater karaoke" simply means, that character can perform underwater. Usually fighting, but can also include other dexterity and strength based actions. It doesn't help singing, talking or breathing underwater.

System


It can be handled:

- As a skill. In my dream with Storytelling system Underwater Karaoke cost like any other skill, but performing actions underwater doesn't use the usual attribute + skill combination, but Underwater Karaoke + skill. The point is, that Underwater Karaoke as a skill is cheaper to buy and advance than an attribute, and it also covers both Strength and Dexterity.
(It is overpowered skill (underwater) and really unbalanced. But it was a dream and I just write it down here. From this point ideas were not in my dream, but I present them as I write).
- As an advantage. It can be an advantage (in ST system, or basically in any system what uses advantages). Cost for oWoD games could be 2pt merit.
- As a feat. For D&D players Underwater Karaoke is a feat. It could be bought by more physical classes (like fighter, rogue, monk etc.). I don't see any other restrictions here.

Side Note


I somewhere have heard, that in fantasy games (or games in general) where swimming is a skill, you actually need to sacrifice your precious character creation and development point, it is rarely taken. In fantasy it is realistic. Swimming wasn't that popular. In modern games swimming is usually included in Stamina/acrobatics etc. and isn't necessarily a skill of it's own. But if swimming was it's own skill, what does cost as much to buy and develope than... for example spell crafting, swordsmanship, survival and others, how many characters you know who are really good swimmers?
Usually andventures take place in dungeons, cities, forests, generally on solid ground. They might go near the water, but usually with ships. If you are in the water, you have been:

1. Thrown there
2. Fumbled your roll there
3. Escaped burning ship there

So, is Underwater Karaoke that unbalanced? It makes your character awesome in water considered to other characters, but how often it is used? 1/10 sessions? I don't remember when my player's character was in water performing something. And I remember games of Vampire: the Masquerade, Fading Suns (there was this water planet, but they only dipped their feet on the water. Oh, and character swam with native alien race for laughs), Dungeons & Dragons, Praedor... and many others.

But if the adventure's main theme is around the water, it is completely acceptable, that even one of the characters can perform better in the water than others. Because otherwise the whole campaign would be just -X to your character because you are in water. Like if campaign is set in water, it is norm like campaign set in solid ground. You create first level character, but because of your GM thought it would be cool to set the scenario in water enviroment your character is actually -25% (example) lousier than in a campaign, where is more solid ground.

So, concider this skill/advantage/feat, and give it a shot. And the name Underwater Karaoke is kickin' awesome!