South Port plans to buy a new mobile harbour crane to handle growing cargo volumes at Bluff.
The deal is worth $6 million and is the port's largest capital expenditure since it was established in 1989.
Chairman, John Harrington, says South Port has achieved consistent growth since a global container shipping link by MSC was re-established in May 2008, and the investment shows confidence in the port's ability handle future container volumes.
The new crane will replace a smaller one at the port and the company will also buy another heavy lift container forklift for about $750,000.
Shares in South Port rose 5 cents to $2.60 on the announcement.