Mercator inflates area by sec²(latitude): nothing on the equator, about double at 45°, and more than triple past 55°.
Because Montanhas do Tumucumaque National Park sits at 2°N, the map draws it at very nearly its true size. Netherlands, far higher in latitude, is inflated much more — which is exactly why, on screen, it can look the equal or the larger of the two even though the true areas above say otherwise.