Emergency services recovered Ku from the sea, but she was already unconscious and attempts to resuscitate her at the local hospital failed.
Ku, who was 25 and from the capital Taipei, was said to have been a scuba-diver for three years and to have been a regular volunteer on beach clean-ups in the area.
In professional modelling sessions it is normal for the model to switch repeatedly between scuba and breath-hold, and the shoots normally take place in well-lit shallow waters. The session on which Ku died was said to have involved at least one underwater costume change.
Eelin Entertainment, Ku’s modelling agency, told reporters that the shoot was not work-related but a personal project, although there have also been press reports that agency representatives were present at the time. What was unclear was whether support divers were in place.
There were also reports that Ku’s family had said that she was recovering from flu at the time, and that she may have suffered from asthma.
Ku was married, with a four-year-old daughter. An investigation into her death is now under way.