A recent Master's thesis has found a Milford Sound tsunami - triggered by a landslide - may leave no survivors, with as many as 3500 dying if the wave hits during the peak of the tourist season.

The new modelling, which builds on more than a decade of research, shows the best chance of survival relies on people running for higher ground before the shaking stops.

The best-case scenario shows 5.2 percent of people would survive the wave, and in this case the tsunami would have to hit at night, during the winter offseason, when only a few hundred people would be in the area.

Edited title to make it sound less like there was just a tsunami and everyone died.