The underwater vortex effect. Allow your party to explore the depths while breathing air and staying dry (mostly). The Webm is 1000 x1000 pixels so you can scale it to fit your needs. Also, comes with the water vortex sound file to help sell the effect to your players. Once downloaded the file will only render correctly on Foundry VTT. If you try to view it in a media player like VLC it will look strange and pixelated. The map is a free variant by https://www.patreon.com/czepeku