A P J Abdul Kalam Monday created history by becoming the country's first President to undertake an undersea journey in a submarine.
Kalam boarded the INS Sindhurakshak, a Russian-origin kilo class submarine, from the naval dockyard at around 11 am, a naval spokesman said in Visakhapatnam.
The duration of the journey is around three-and-half hours during which Kalam will have lunch with the crew members, he said.
The President would be briefed on the intricacies of submarine operations, the spokesman said.
The INS Sindhurakshak would sail 20 nautical miles from the shore and would go 40 mt deep, he added.
The submarine, which usually accommodates 60 crew, is carrying eight additional passengers -- including Kalam and members of his entourage.
The submarine is accompanied by a destroyer ship, which will be tracked by the submarine for a simulated torpedo attack.
Instead of a real torpedo, the submarine would let fly a dummy water shot at the ship to demonstrate the attacking capabilities of the craft, the spokesman said.
Kalam's submarine trip comes a day after he undertook a presidential review of the country's naval fleet.
Kalam had previously visited a submarine in harbour when he was scientific advisor to the defence ministry.
Former Defence Minister George Fernandes had spent a night underwater in INS Sindhuveer submarine during his visit to the Eastern Naval Command centre in Visakhapatnam in May, 2003.
In 1988, late prime minister Rajiv Gandhi had also visited nuclear submarine INS Chakra at Visakhapatnam.