The Water Obelisk is a Farm building. You can purchase it from the Wizard after completing the Goblin Problem Quest. Interacting with the obelisk will transport you to the beach, the same as the Warp Totem: Beach. If you wish to move the location of your Water Obelisk after placing it, you can do so by talking to the Wizard.
|1,000,000g||5 Iridium Bar|