Foreigners are not authorised to own land along the Colombian  coastlines and in border regions with neighbouring countries. For the purposes of the OECD FDI RR Index, the restriction on access to land in border areas is assumed for national security reasons and, hence, not considered as a restriction. Only the restriction on access to land in coast areas is taken into account.
"Article 5 The vacant lots located on the national coasts and in the border regions with the neighboring nations, whether it is the intermediate lots reserved by article 52 of the Fiscal Code or the non-reserved ones, will henceforth be adjudicated in accordance with the Current provisions on the matter, only to Colombians by birth. 
Paragraph. The vacant land acquired in accordance with this article may not be transferred to foreigners under any title.[...]" (Decree no. 1415 regarding assignment of vacant land (18 July 1940), Article 5 [google translation])
Decree no. 1415 regarding assignment of vacant land (18 July 1940), Article 5
[<a href="http://www.suin-juriscol.gov.co/viewDocument.asp?ruta=Decretos/1282551">Decree</a>]