The lower part of Central America is in the south-west of Costa Rica ( south of 10 ° N ) and Panama , including the islands of Rey , Contador , Cébaco and Suscantupu. The southern part of America is east of the Andes and north of the central ridge of the Cordilleras in Colombia , as well as north of the eastern Cordilleras and north of Venezuela , in the Cordillera de Merida region , in the tract of the Orinoco River and east of its delta , to north and west of the Guiana Highlands ; on the islands of Margarita , Trinidad and Tobago .