+ AA6YQ comments below

I am not sure that it can proven that it is above or below water. 

+ The traditional approach would be to visit the rocks in a boat at high tide on a calm day, and measure the distance between the tops of the rocks and the ocean surface.

+ Alternatively, we can analyze pictures of the rocks taken during previous DXpeditions, determine their height above sea level at high tide, and compare that to the subsequent rise in global sea level to determine if the rocks are still above sea level at high tide.

+ Here's what Wikipedia has to say:

"Scarborough Shoal forms a triangle-shaped chain of reefs and rocks with a perimeter of 46 km (29 mi). It covers an area of 150 km2 (58 sq mi), including an inner lagoon. The shoal's highest point, South Rock, is 1.8 m (5 ft 11 in) above sea-level at high tide. Located north of it is a channel, approximately 370 m (1,214 ft) wide and 9–11 m (30–36 ft) deep, leading into the lagoon. Several other coral rocks encircle the lagoon, forming a large atoll"

<https://en.wikipedia.org/wiki/Scarborough_Shoal>

          73,

                 Dave, AA6YQ