Matevulu blue hole, Sanma Province ... Pristine: Blue Hole, Espiritu Santo, Vanuatu. Credit: Alamy To look at her contented string of ponies, however, you'd never guess of their past suffering.

The river starts to change colour and becomes distinctly bluer as you get closer to the Matevulu ... arrive at a neon blue swimming hole.SUPPLIED / Not-For-Syndication Santo, as it is ...