When you’re just north of the bridge, use the key to feel for the chest. Hot is close and cold is far. When the chest is right below your feet, use the spade to dig it up.
Use the key on the chest to unlock it.
Droalak[]
Items needed: Ghostspeak amulet, sapphire amulet, and two ecto tokens or enough money to buy a charter boat to Port Phasmatys if Ghosts Ahoy has not been completed
You can read an incomplete list of all your exploits during the quest on the bookcase at the Outpost, but cannot take it away.
You can return to Droalak in Port Phasmatys after the quest and upon learning of what happened, he will finally be at peace and will disappear. Doing so is a requirement for obtaining the master quest cape.
You can talk to Historian Minas in the Varrock Museum to receive 5 Kudos.