Monsters for a seafarin' campaign?

[Togath]

So as part of my most recent campaign, I'm trying to come up with a decent roster of critters to throw at my party while they sail around, as well as during their time on small islands, delving into coastal caves, and in port towns.
The catch is, I'm currently building stuff for a 3-6 level range(it will go higher eventually, but slowly), and I want some stuff that can reasonably harass them while on a medium sized ship.
It seems like there's plenty of later CR stuff, as well as a lot of fully aquatic monsters, but my ideas are running a little low for these earlier game threats.
The environments vary, but so far mainly range from warm-temperate to low-tropical.

Draugr are one creature that caught my eye, cr 2 each and that climb mod might help with boarding a ship from the sea(are there any rules for that?), and maybe... octopuses with the advanced or giant template?
Anything that flies is obviously an option, but I worry it might get a little dull if they only fight land-based-stuff-but-on-a-ship and flying foes(maybe whip up flying fish and squid to harass them?).

I have considered stuff with reach, but did hit two problems;
A: most stuff that swims and has reach seems high cr, and B: I don't know if reach actually lets you potentially smack stuff on deck while swimming.

I am open to third party or even homebrew suggestions too, if anything fun comes to mind.:smallsmile:
So, any neat ideas this sparks? Anything fun you've used against your own players in the past?

[unseenmage]

I suggest popping by the PF forums and having a look at the Skull and Shackled AP threads for ideas. Even better, snag yourself a copy of the adventure and have a readthrough. A warning though, most of the complaints I remember about the monsters contained therein were that they ALL had a grab special attack of some kind or another.

Am trying to remember more specific details from the one time I actually read through the thing...

The Grindylow (http://paizo.com/pathfinderRPG/prd/bestiary2/grindylow.html) was a recurrent menace throughout the early levels.

I had planned on attacking my players with some Wyrwood (http://archivesofnethys.com/MonsterDisplay.aspx?ItemName=Wyrwood) reskinned as shipwreck golems too if that game hadn't died.

For third party ideas I am a devout fan of the Amalgam (http://www.d20pfsrd.com/bestiary/monster-listings/templates/amalgam-creature-cr-special/) template from Green Ronin's Advanced Bestiary. The basic gist is, take two creatures, stick them together, retain the best traits of each as best you can, use the higher of their CRs and HDs, and voila, new interesting creature.

[Manyasone]

For all your aquatic needs you can check the Cerulean Seas Bestiary. Nice stuff

[weckar]

Unleash the Kraken? Not all encounters are meant to be fought, after all.

[ksbsnowowl]

Merro (aquatic ogres) and scrags (aquatic trolls) are in the first MM, and right in that CR range. They work both on ship and coastally. Sea hags, too.