An Auckland ferry company could face a fine as high as $500,000 after passengers were injured during a trip to Waiheke.

Maritime New Zealand confirmed a charge had been laid against Explore Group NZ, which runs a ferry service between the island and Auckland CBD.

The prosecution came about after an incident on September 1 on the company's "Discovery 5" ferry when female passengers were outside on the deck as the vessel was hit by a large wave.

It is understood they suffered leg injuries.


The charge of failing ensure the safety of those on board could see Explore fined as much as $500,000.

A Maritime New Zealand spokesman also confirmed the "master of the vessel" had been charged and personally faced a fine of up to $250,000.

They will appear before Auckland District Court next month.

Explore have not yet responded to requests for comment.

Meanwhile, another ferry company -- Fullers -- last month pleaded guilty to two health and safety breaches after a crash that injured more than a dozen people.

The 27-year-old vessel, Kea, was carrying 61 passengers when it hit Victoria Wharf at Devonport on February 17 last year.

Ambulances took 17 people, including a crew member, to North Shore Hospital and a Takapuna accident clinic with injuries ranging from a head gash to a suspected broken arm.

The company will be sentenced next month.