Spell or Item to give a Swim speed

[henebry]

I'm working up a magic item that would grant the user a listed swim speed (and not just a bonus on swim checks, like the Ring of Swimming). Animals with a listed swim speed don't need to make swim checks to move. And they have much higher speeds in the water than humans and gnomes.

To create the item, though, I need first to find a spell with the appropriate effect.

It's possible that a listed swim speed is already an implicit effect of the Water Breathing spell. The Swim skill roll covers two separate issues: Are you drowning? and Are you making progress through the water? Casting a Water Breathing spell means you don't have to make Swim checks to avoid drowning, but a DM might still rule that you have to make Swim checks to move in the face of a strong current. OR a DM might simply give a listed swim speed = 1/4 your land speed, duplicating the effect of successful Swim checks (on a successful check you can move 1/4 land speed as a move action or 1/2 your land speed as a full action). What do you folks think so far?

Does there exist a true swim spell in Stormwrack (or whatever that water-focused supplement is titled)?

What I'd really like is a spell that gives characters a Swim speed of 60", like that of sharks. Fly gives a similar speed and lasts for just 1 min/level, while Water Breathing lasts 2 hrs/level; both are 3rd level spells. The other key difference is that Fly affects just one creature, while Water Breathing can be divided among as many as you like, though the spell's duration is thereby divided up as well. Assuming that my new spell (I'll call it Gills and Fins for now) functions as an improved version of Water Breathing, radically increasing water speed, I'm inclined to make it a 4th level spell which lasts 2 hrs/caster level. And Gills and Fins can be divided among as many characters as one chooses to touch while casting the spell.

[fangthane]

As a fourth level spell granting a swim speed (I'd specifically word it as a swim base speed equal to the creature's land base speed) and water breathing, I'd do this:
up to 1 target per 3 caster levels
10 minutes per level
Touch range
And of course it'd include the WB component.

I'd have it produce gill slits on the creature's neck, to be used in addition or in preference to the creature's windpipe, make 'em bald and buoyant and grow hand/feet webbing (+10 to swim checks), and reduce land speed to 2/3 normal. Definitely a transmutation spell, if not necessarily a polymorph.

[Destro_Yersul]

You could always base it off the cloak of the manta ray.
From the SRD:

Cloak of the Manta Ray
This cloak appears to be made of leather until the wearer enters salt water. At that time the cloak of the manta ray adheres to the individual, and he appears nearly identical to a manta ray (as the polymorph spell, except that it allows only manta ray form). He gains a +3 natural armor bonus, the ability to breathe underwater, and a swim speed of 60 feet, like a real manta ray.

Although the cloak does not enable the wearer to bite opponents as a manta ray does, it does have a tail spine that can be used to strike at opponents behind the wearer, dealing 1d6 points of damage. This attack can be used in addition to any other attack the character has, using his highest melee attack bonus. The wearer can release his arms from the cloak without sacrificing underwater movement if so desired.

Moderate transmutation; CL 9th; Craft Wondrous Item, polymorph, water breathing; Price 7,200 gp;Weight 1 lb.