With just a wet suit and a brush, Mr Martin and his team bravely spend up to seven hours a day in the depths of the tank which is home to an array of shark species including nurse, zebra, bamboo and six deadly sand tiger sharks.
The biggest of them all is a sand tiger called 'Storm' who weighs a massive 650lb and is more than 12ft long.
Mr Martin said: 'I was petrified of sharks as a kid mainly because of the Jaws films and they are large potentially dangerous animals.