Maritime New Zealand (MNZ) confirmed the sinking after flying over the wreck yesterday.
"The Bay of Plenty and Coromandel communities are advised that the sinking of the stern section will likely result in the loss of more debris and small amounts of oil into the sea,'' Ross Henderson of MNZ said.
A light sheen of oil stretches for about a kilometre north-west of the wreck, but the volume of oil released was "only a tiny percentage" of what was spewed into the ocean in October.
The forward section of the ship was still holding on the reef, but the back portion of it had suffered further damage.
"A wave of over 12 metres was recorded at the reef overnight, with winds of 27 knots (50kmh) and seas of 8-9m experienced today," Henderson said.
Rena hit the reef in the early hours of October 5, after cutting a corner to try to make up time to meet a deadline at Port of Tauranga.
A picture of the Rena when she first ground ashore on the Astrolabe Reef:
And a picture of it now:
Read more here:
http://tvnz.co.nz/national-news/rena-s-stern-sinks-in-rough-seas-4816289
And here:
http://www.stuff.co.nz/national/6690100/Rena-takes-a-battering/
View where it is in Google Maps:
http://maps.google.co.nz/maps/ms?msid=212558459733996054523.0004afa0c2bea07ddbc72&msa=0&ll=-37.550838,176.393738&spn=0.211764,0.528374
