You want to set up on the ledge at the top level of the zone, right where you would get out of the pool of water after swimming up the tube. Its at -100, 100 and can be reached by running invis from the West Wastes zoneline. Nothing sees invis up to that point, so it is easy to reach.
It has one wandering mob, usually a Molkor, which will path back there and see you eventually, so you have to be able to kill that and should do so first to break the camp in.
Your force is borderline able to kill a Molkor. The can CHeal and Gate, and you don't have Mana sieve so you will need to rely on stuns/bash from the Paladin, and they're modately resistant. I think its possible, but you might run into some problems.
Assuming you're able to kill a Molkor at all, this location has everything you need. Its possible to easily get a number of Molkors single without an FD puller here, watch for pathing and avoid the pair guarding the hut with the tube down to the dark temple.
There are two single pullable seahorses you can camp for seahorse related items in the pool next to you. There are also a pair of servant swordfish in the tunnel leading to teh dark temple tube, around the 50,0 point. The druid should be able to charm one to help kill the other.
https://wiki.project1999.com/Annotat...ns_Grotto_Maps has most of the stuff marked, though I didn't put the swordfish pair on this map when I made it.
EDIT: Right, the seashell! Easiest here by far is to buy one, as many of these drop whenever a guild clears large blocks of sirens for Flawless Diamond farming, which doesn't happen often but it does happen enough that they're not very costly.
If you don't want to buy the seashell, you want the Eastern Siren temple. How effectively you can deal with them will in a very large part depend on how good your MR is, as the enchanter sirens are easy if you're high enough level to resist everything, but otherwise will charm/slow/gflux you into problems. The cleric ones will have the same problem as the Molkors, in that you need to stun them.
I wrote a guide to doing that part here:
https://wiki.project1999.com/Siren_Hunting . Spent a good chunk of time duoing the area with a Torpor shammy back when you could interrupt cheal with push.