Underwater Quest question

I have done the Shrine Quest and now i need to go to the Underwatercity but i only got one Underwaterhelmet where can i got 5 more for my Party ?? And where can i find shells to sell them to the Shipseller ?? Thx for your helping

The quest from Buckley (the shipseller) is to bring him 3 conch shells, for which he pays you $200. He makes the masks and rebreathers (those look exactly like the conch shells but work more like a scuba tank). You can then buy those from him. He doesn't always make the same amount of anything -- per conch shell delivery, he might make 3 masks, 3 rebreathers, or any combination thereof. You will get through Collasium best (least use of "Breath of Air" spell) if you have one rebreather and one mask per member of your party. You get the conch shells either by stealing them from the Crabs O' The Sea or by killing the same. If your pickpocket skill is high, you stand a better chance of getting a shell that way. Most of us have found that turning the spawn rate to often and having a party member with good scouting skills helps.