November 2022: Free diving/snorkelling and heart conditions

This safety update is for operators of commercial vessels that offer free diving/snorkelling for passengers.


In 2021, a commercial charter vessel anchored at a bay in the North Island so passengers could free dive for kaimoana. A short time after diving began, one passenger was found to be unconscious.

The vessel had a well-documented plan in place for diving medical emergencies. This plan was implemented and the person was retrieved from the water and taken aboard the vessel. The crew tried to resuscitate the passenger but unfortunately, when the vessel arrived at a nearby port, paramedics declared the person dead. A post mortem identified that the death was attributed to severe ischemic heart disease (also called ‘coronary heart disease’). Dive safety organisation, Divers Alert Network, states about one-third of all diving fatalities are associated with an acute cardiac event. It recommends that people with active ischemic heart disease not undertake diving activities (including free diving/snorkelling).

In this case, the skipper did not know the passenger had a heart condition that could put the person’s health and safety at risk when free diving.


Safety reminder

Operators of commercial vessels that offer free diving/snorkelling are reminded of their primary duty of care under the Health and Safety at Work Act 2015 (HSWA) to ensure, so far as is reasonably practicable, that work carried out as part of their business or undertaking does not put the health and safety of other persons (for example, customers or passengers) at risk. As part of their risk assessment process, operators should:

1. Assess whether passengers are fit for free diving/snorkelling

Assessing whether a passenger is fit for free diving/snorkelling might include asking passengers questions such as:

  • their age
  • their physical fitness
  • their free diving/snorkelling experience including if they recently completed a dive in similar conditions, and
  • whether they have a heart condition.

Operators should also consider:

  • the risks involved in free diving/snorkelling
  • their workers’ level of experience and ability to supervise at-risk passengers
  • the equipment they have available (for example, resuscitation equipment)
  • environmental conditions (for example, weather and sea conditions).

2. Make sure passengers are aware of the health and safety risks of free diving/snorkelling with a heart condition

At the booking stage, operators should inform passengers that free diving/snorkelling can be a strenuous physical activity, even in calm water and there are serious risks associated with some medical conditions, especially heart conditions.

Whether this information is on the booking page of the operator’s website, printed on the booking form, or delivered verbally over the phone or in person, the advice should include asking people with a heart condition to check with their doctor, before they book, if free diving/snorkelling is a suitable activity for them.

Operators should also make sure this information is included in the health and safety briefing given to passengers on the day of the activity.

It is a good idea to have a range of ways of providing the information especially if English is not the passenger’s primary language (see diagram below).

Using Diagrams For Instructions
Diagram courtesy of Worksafe New Zealand


More information

Divers Alert Network []


Contact us for more help

If you have any questions about this safety update, please contact our Wellington office.


New Zealand (toll free):
0508 225 522

Tell us what you need help with and remember to include your contact details (email address and phone numbers).