46 AB18, Urumpirai North.
|Karst Spring Cenote
|Folkart (1865): Poottoor Well The Journal of the Ceylon Branch of the Royal Asiatic Society of Great Britain & Ireland, 4(13), pp 123-127. online online
|Nilavarai Bottomless Well, 46 AB18, Urumpirai North.
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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නිලාවරයි නොසිඳෙන (Nilavarai Bottomless Well) or நிலாவரை கிணறு (Moonwell) is famous for the fact that its production is quite high and that it never runs dry, even during severe drought. The explanation is simple, it is a collapse doline which connects to the water filled limestone cave below, in other words to the groundwater. The spring was enclosed with a wall and forms an 8 x 12 m lake. A flight of steps leads down to the water level which is 4 m below the surface.
There are a lot of rumours about the well, the most spectacular obviously that it is bottomless. It is definitely quite deep, but we are convinced someone has measured the depth. Also, the locals tell that the upper 12 m of water are sweet water, but below there is salt water. This is quite likely, as the area is only 10 m asl, and 6 km from the sea and 3 km from the seawater marshes to the east. The sweet water enters the groundwater from the surface, the seawater flows into the caves from the coast below.
But actually the salt water story was scientifically studied in the mid 19th century and was published in the 1865-66 edition of the Journal of the Ceylon Branch of the Royal Asiatic Society of Great Britain & Ireland. Samples of water were taken at the depths of 14 m, 29 m and 44 m using a special instrument with a valve. The bottles with probes were sent to England for chemical analysis. They found that the well was not bottomless, though it was between 45 m and 46 m deep. The probes from the bottom smelled strongly of sulphured hydrogen. The water became brackish at a depth of 14 m to 15 m. They also compared the tides of the nearby sea, with level changes in th spring. The result was mysterious, the water levels in the well alternated three times a day while the tides alternated twice a day. The reason for the thrice daily water level changes in the well was not found.
A recent exploration, more than 150 years later, was done with an automated diving robot and by divers of the Sri Lankan Navy. They reached the ground of the well, which was at a depth of 52.5 m. The fresh water was 18.3 m deep. The divers discovered a number of caver passages at various depths and three carts at the floor, which fell into the well. They also found the torso of a Buddha sculputre carved from limestone from the area.
Another typical legend is also told, the underground connection to the Keerimalai Sacred Water Spring. This is also quite likely, as the whole area is drained by a karst cave and the karst springs are actually connected. The only part of the legends, which is definitely nonsense, is actually the story that a lemon thrown into the water reappears at Keerimalai. It's pretty simple: as long as the lemon swims it will never go through the underground cave.
There is an explanatory sign at the well which is in three languages including english. Otherwise, it has no touristic development at all.