Mysterious bubbling sand at Changi

Last Tuesday I was at Changi Beach and I encountered this phenomenon that I have no idea what was happening.

Please play the video (13 seconds in length) to take a look. The sound at the background comes from the wind, not from the bubbling itself, so please ignore it.



There was a tidal pool of continuous bubbling sand and I was surprised and puzzled. I tried to use a twig to check the bubbling out but apparently, it seems deep where I couldn't reach the bottom. Yet, I managed to dig out a Thumbs-up sea squirt (probably Polycarpa sp.) from it but the bubbling did not cease.

Did anyone have any idea what was happening? I have friends thinking it's a hotspring.

Feel free to leave your comments, would like to hear your two cents worth.