On 18 June 2023, five people died aboard a submersible which was en route to the wreck of the Titanic - 3,800 metres beneath the waves in the North Atlantic Ocean.
The Titan submersible, operated by the American tourism company OceanGate, imploded 90 minutes into the journey - killing all passengers.
New Zealander Rob McCallum, who himself runs expeditions to remote places through his company EYOS Expeditions.
Five years prior to the disaster, Rob raised concerns with OceanGate about the risks of the vessel's carbon fibre and titanium construction.
In March 2018, he emailed OceanGate founder Stockton Rush to warn him about the dangers of their submersible and that he was risking lives.
Stockton Rush died in the implosion along with four others. Rob McCallum speaks to Kathryn Ryan.
