The photos are the work of retired literature teacher Luu Duc Ngo, who has spent most of his free time trying to capture the illusive and mythical turtles.

The legend of Hoan Kiem Lake turtles has been part of Vietnamese folklore for generations, and sightings are believed to be auspicious. However, few have actually seen the lake's turtles - including those who live and work nearby.

To discourage doubters, Mr Ngo has made it his life's work to keep the legend of the turtles alive. Everyday, he spends at least two hours cycling around the lake on the off chance that one of the shy and retiring turtles will raise its head.

Mr Ngo sells his photos on the streets, in schools and elsewhere he finds an appreciative audience. Proceeds go toward charitable activities.

The Temple of Literature exhibition features more than a hundred photos Mr Ngo has taken over the last three years, together with articles about the legendary turtles.

The exhibition will run until April 15. The photos will then be exhibited at the Vietnam Culture and Arts Centre and Thang Long Royal Citadel to celebrate the 117^th birth anniversary of the late President Ho Chi Minh on May 19.