The most popular and also the largest of Santo's blue holes is the Matevulu Blue Hole on the eastern side of the island.
These blue holes are freshwater holes where the underlying limestone has reached down to the water table, resulting in magnificently blue swimming holes in numerous locations on the island. Blue holes also contain a number of freshwater fish species.
They are a spring in a Karst environment. One characteristic of a Karst environment is that water, which drains quickly through the limestone in one area, surfaces in another. Karst environments only have subterranean drainage, and there are no bodies of water above ground. Therefore, the size of the blue holes depends greatly on the level of rainfall, though they usually never entirely dries out.
Before logging your cache please answer the following simple questions and send them through my profile.
1) Describe in your own words the color of the blue hole today. Why do you think the water is that color?
2) Estimate the approximate width, length, and maximum depth of the blue hole area. How did you perform your depth measurement?
3) Are the sides vertical or sloping? Why do you think the sides are that shape?
You can log right away and do not need to wait for a reply! Photos are appreciated but of course voluntary.
It is possible to enter the area with a kayak tour or privately by a car/taxi (via the lost place airfield). There is a small charge for the swim and swing(!). You can do the Earthcache without paying, it may be a bit awkward though.