[PF] Character for Underwater-Dungeoncrawl Oneshot (lvl 8)

[Feint's End]

Hey everybody. I'll participate in a oneshot PF Dungeoncrawl in a few weeks and since it is just for one afternoon I thought I'd try something fun and powerful ... only problem is I'm not sure what exactly will be fun and powerful.

I know a few things which limit the choices somewhat and make some build unreliable. First of all there are only 5 races allowed: Undine, Gillmen, Grippli, Lizardfolk and Merfolk (all with swimspeed) and as you see from the title it will play out underwater.

I know of two player so far:
-a Gripplie summoner ... I helped him optimize his Eidolon and now it deals an average of around 100 dpr if all attacks hit (with a to hit of +16)
-an offensive support cleric (no idea what the player meant by that but at least I know it's a cleric)
-??? (I don't exactly know how many other players there are and what they will play ... I think 1-2 more)

I thought about Gunslinger or Zen Archer (because range is awesome) but they won't work in an underwater adventure.

Allowed Material is: Core, ARG, APG, UC, UM

I can build a very strong character (like Mid OP Caster or High OP Melee) as long as it has a good flavour (even though it is a one shot the DM has a storyline planned as far as I know)

Since I don't know about the other players and we already have a melee brute I am not sure now on what to play. I'd like to have an interesting concept since that way I lower the chance to have the same role as somebody else in the group.
I'd like to go ranged but I'm not sure if any classcombination work on that level and especially underwater ... now if psionics would be on the table ... (sadly they are not since the DM is unfamiliar with them ... only the books I wrote above)

Input is appreciated

[hemming]

The DM won't allow you to bring in Aquatic shot feat from 3.5 or the aquatic bow or aquatic crossbow?

Your range is still limited compared to on land but it would give an option

[Feint's End]

The DM won't allow you to bring in Aquatic shot feat from 3.5 or the aquatic bow or aquatic crossbow?

Your range is still limited compared to on land but it would give an option

Yeah I thought about using Aquatic Shot together with an Aquatic Bow and Zen Archer but I'm not sure the DM would allow it (I can ask him tomorrow).

I'm also looking for some general suggestions on what to play and not just for a ranged character so if anybody got a good, powerful and flavourful idea bring 'em on (that's a lot to ask I know).

[hemming]

The only undersea specific class I know of is wavekeeper - but its a 3.5 druid class and I'm sure not the best for optimizing. Always thought it looked neat from a flavor perspective (control the waves and currents around you).