I use pillars and ceiling tiles to make a foundation under the water where it is not easy to see. As long as one wall is connecting the underwater foundation to the above floor you want to make, the floor will stay afloat. This allows some very creative base building. From swimming pools in your living room to an underground piranha pond in your basement, the possibilities are endless.
With major updates coming every week for this Early Access title, my method might be changed in future updates. I will strive to update this video as building methods are overhauled. Feel free to ask me any questions about building methods in Ark, I always enjoy helping new Arkitects.
This game is still in the Early Access phase for PC, Mac, and Linux but will be available for the PlayStation 4 and Xbox One in the next few months.
