if you're looking for something sort of WoW-ish, you'd probably be better off with a spontaneous caster... the play style will be more similar to the video game than having to learn to prepare spells each day. For dealing with water, think about the following race options:
- Undine have a natural swim speed and can take a racial alternative to gain the amphibious subtype (allows them to naturally breathe air or water). that would be awfully useful, their stat adjustments aren't ideal for a spontaneous caster though.
- a Human could take racial heritage [undine] and aquatic ancestry for its starting feats and also gain the amphibious subtype. that eats up both 1st level feats but allows you to put +2 racial in Cha.
- an Aasimar has better racial bonuses than humans (with lots of ways to get +2 cha) and can take the 'scion of humanity' alternate to qualify for racial heritage/aquatic ancestry (though then you're investing your 1st and 3rd level feats...)
For a frost mage type:
- a winter oracle could actually be a really good route; they get a bunch of the decent cold spells plus a ton of special cold-based powers (including freezing spells, which is very frost mage-esque). you could also add to their special powers by picking up the eldritch heritage feats for boreal, elemental[cold], or marid.
- obviously you could do something similar with an actual sorcerer. they get a wider selection of cold spells, but less powers. you can make up for that somewhat by also picking another bloodline through eldritch heritage (but there's no way to get freezing spell here unless you multiclass).
- this isn't a spontaneous build but the winter witch (both an archetype and a prestige class- both worth taking) gets the spells you want and some decent hexes that go with the theme. you're stats are good enough that you could easily still take eldritch heritage even being Int based.
For a summoner type- unfortunately, you can't really pull this off in pathfinder (unless you're playing a gestalt campaign) but here's the closest ways i can come:
- a summoner. the eidolon is exactly what you want to build a Void Walker, Fel Hunter/Hound, or whatever they use nowadays; unfortunately they don't really get any of the right spells- make a samsaran with the 'mystic past life' alternate to add a handful of signature warlock-type spells to your list and take the eldritch heritage [arcane] feats to add a few more starting at 11th level.
- an oracle... the focus here is on getting the powers right. the bones and occult mysteries both have some really appropriate powers. take the arcane heritage feats again, use the 11th level to add a few signature spells; take improved familiar at 5th or 7th and grab an Imp for your pet.
- a sorcerer... this is all about getting the spells right. the arcane bloodline sets you up for improved familiar; the abyssal bloodline has some nice perks if you want to be summoning evil outsiders to help you (would pair nicely with augment/superior summoning feats); the infernal bloodline has some nice fear based things. if you choose either of the second 2 you can always add the Imp through eldritch heritage too (or crossblooded, but i've always felt like the penalty for crossblooded is pretty stiff).
edit: in a water based game you will definitely run into more things with cold resistance than usual... if you want to go fire based there are plenty of ways to do that- remember that casting fire spells underwater requires checks and stuff (but look at the "steam caster" feat available to undine, or anyone with racial heritage[undine])
summoner is out DM rules them over powered
i don't blame him- they're easy to make very powerful (which makes them fitting warlocks, lol).
i hope there is something in there that will be useful to you. if you have specific questions about anything don't be afraid to post them (or even PM me)
winter is an oracle mystery. you can find it here.
(that website, d20pfsrd, is an incredible resource for pathfinder rules elements)
edit: you're new to pathfinder... oracle is like a divine sorcerer- here's the class info from the advanced players guide.
you have to pick your curse carefully... some of them are devastating and some have very little negative impact. you weren't planning to be the face (or at least didn't say you were) so 'wasting' would have virtually no downside- and you could have it look like some kind of chronic frostbite instead of being more leperosy-like. tongues can totally be negated by party members taking your curse language as a language known (in that campaign it sounds like Aquan is probably a language most/all will want anyways). haunted isn't that bad to begin with and (i think) a handy haversack largely negates the mechanical effect.
edit: you certainly have the stats to pull off arcane archer. Undine have decent stats for it too (if you want to take that route)- for your casting take a wildblooded sorcerer with the empyreal bloodline (it switches your casting to Wis which you get a racial +2 to). the only real downside is that ranged weapons utterly suck underwater (but your stats are good enough to have a back up plan).