Of the 88 containers washed overboard from the container ship Rena on October 11, there are 56 unaccounted for.

The container recovery company, Braemar Howells, is undertaking sonar surveys of the surrounding seabed in an effort to find them – they have identified 32 and recovered 19.

Rena had 1368 containers aboard when it struck the Astrolabe Reef – there are now 1280 with 88 having fallen overboard. Photo taken Friday, November 11 by LOC.

Containers from Rena have been found a considerable distance from the Astrolabe Reef where she ran aground on October 5.

Finding containers aground in the Eastern Bay near Te Kaha lends weight to fears the mostly empty boxes could still be floating semi submerged, and perhaps heading for the Chatham Islands.

A Seahorse Kontiki that went missing off Papamoa Beach some years ago was found many months later 200 miles north of the Chathams by a fishing boat.

The seahorse which was identified through its serial number was covered in marine growth, but still afloat.

Rena's missing 56 containers join the estimated 2000-10,000 containers that are lost overboard every year, and they sink boats.

Made of steel, sharp edged and massing many tonnes, a container will make short work of timber, composites, and even aluminium and thin steel plating in rough conditions.

Three weeks ago solo French racing sailor Mathieu Claveau's small yacht hit a ‘hard object' in the middle of the Atlantic and sank.

Two weeks ago five South African sailors were rescued after their yacht The Wizard struck what they believe was a container and sank off Maputo in Mozambique.

Its five crew members were found in a life raft some hours after the yacht sank.

Many lost containers are believed to be able to float indefinitely because of the amount of polystyrene insulation contained in packing.

Maritime New Zealand salvage advisor Jon Walker says aerial searches for Rena's containers were undertaken after the October 11 storm and sonar searches of the seabed in the vicinity of the wreck are continuing.