511.As noted above with respect to low-tide elevations, many of the high-tide features in the Spratly Islands have been subjected to substantial human modification as large installations and airstrips have been constructed on them. Desalination facilities have been installed and tillable soil introduced. In some cases, it is now difficult to observe directly the original status of the feature in its natural state. In such circumstances, the Tribunal considers that the Convention requires that the status of a feature be ascertained on the basis of its earlier, natural condition, prior to the onset of significant human modification, taking into account the best available evidence of the previous status of the high-tide features, before intensive modification.