"There was an underwater sequence where we had to shoot with sharks and a cage. For that we were trained in scuba diving. Then there was another one where I had to jump on to a speeding train that was on fire and fight on the train - those were exciting," Imran said.

On the insistence of the director, Imran and other actors of the film, including Sanjay Dutt, Mithun Chakraborty, Ravi Kissen and debutante Shruti Haasan, underwent a one-week theory and practical course in scuba diving in Durban, South Africa, he revealed.

"Soham was very particular about one thing - he wanted each of the actors to perform his or her stunts and so we trained in scuba diving for the underwater scene. It was a strenuous exercise. We used to spend six to eight hours in the water in the mornings, then go for theory classes and then back into the water.

"But it feels great to be a certified scuba diver now," said Imran, who had subscribed to a three-day beginner's course in scuba diving for his earlier film "Kidnap".

Despite the danger involved, Imran agreed to do the stunts on his own.

"Allan has a great fondness for me and he would want my inputs on it (the stunts) every time. While deciding upon a sequence, he would discuss it with me and ask me if I can do it or not and I would just say - 'Yeah, I can do this'. So in a way, we designed the stunts together," he said.

After "Luck", which will release July 24, Imran would be seen in "Delhi Belly" and "Seven Days in Paris".