In [1]: from django.contrib.gis.geos import GEOSGeometry
In [2]: aruba = GEOSGeometry('SRID=4326;LINEARRING (-69.89912109375 12.45200195312499, -69.895703125 12.42299804687499, -69.94218749999999 12.43852539062499, -70.004150390625 12.50048828125, -70.0661
...: 1328125 12.54697265624999, -70.05087890624999 12.59707031249999, -70.035107421875 12.61411132812499, -69.97314453125 12.567626953125, -69.91181640625 12.48046875, -69.89912109375 12.452001953
...: 12499)')
In [3]: aruba.json
Out[3]: '{"coordinates": [[-69.89912109375, 12.45200195312499], [-69.895703125, 12.42299804687499], [-69.94218749999999, 12.43852539062499], [-70.004150390625, 12.50048828125], [-70.06611328125, 12.54697265624999], [-70.05087890624999, 12.59707031249999], [-70.035107421875, 12.61411132812499], [-69.97314453125, 12.567626953125], [-69.91181640625, 12.48046875], [-69.89912109375, 12.45200195312499]], "type": "LinearRing"}'
This GeoJSON is not valid as GeoJSON standard doesn't define LinearRing type.
GeoJSON validity could be checked here: http://geojsonlint.com/
PR