The Defence Force has pleaded guilty to a charge laid over the death of a sailor after a diving training exercise.

Zachary Yarwood died in hospital after a night-time dive at the Devonport Naval Base in March last year.

The 23-year-old had been diving in about six to eight metres of water during advanced dive training before he died.

WorkSafe later charged the Defence Force under the Health and Safety Act, alleging it failed to ensure the safety of its employees.

This morning, the Defence Force pleaded guilty to one representative charge before Judge Ajit Swaran Singh at the Auckland District Court.

Yarwood's family were in court to hear the guilty plea and indicated they wished to speak through victim impact statements at sentencing.

The Defence Force will be sentenced later this year.