Ian Redmond, 30, described by relatives as a wonderful man, was snorkelling just 30ft off Anse Lazio beach on the island of Praslin when the 6ft shark struck.
It was the second fatal shark attack on the beach in less than a fortnight after the death of a 36-year-old French diver on August 2. The latest attack happened on the day the island's government held an emergency meeting to discuss the Frenchmans death.
His new wife Gemma Houghton, 27, who was sunbathing on the beach, heard his screams and witnessed the fatal attack.
She and other holidaymakers on the crowded beach watched helpless as they heard him shout: Help, help.
The attack happened at around 4.30pm yesterday on a beach considered one of the most beautiful in the world.
The couple had only married on August 6 and it was the second week of their honeymoon.
The two deaths are the first in waters around the idyllic Indian Ocean island nation in almost 50 years.
Last night specialist shark hunters were being flown in from South Africa to track down what is thought to be a "rogue" shark stalking the islands waters.
At an emergency meeting last night, the Seychelles interior minister, Joel Morgan, ordered the closure of all surrounding beaches and banned swimming in waters around the scene of the attacks.
The double tragedy comes less than two months after the Duke and Duchess of Cambridge enjoyed a honeymoon on the luxurious North Island only 30 miles away.
Witnesses are said to have looked in horror as holidaymakers in an inflatable dinghy raced to Mr Redmonds aid and saw the shark in the water nearby.
He was brought ashore and rushed to hospital by helicopter but he was pronounced dead from massive blood loss.
Initial reports said that he had lost a leg and had suffered bite wounds to an arm.
One American tourist said: "Someone had seen a fin sticking out of the water, and then we saw a dinghy pulling a man from the water.
"I saw the swimmer, who was missing a huge chunk of flesh from his left leg, so much so that I could see the bone of his thigh. He was sickeningly pale, but still had his flippers on both feet.
"At this point a woman ran over and started screaming. She said: Thats my husband!"
"Someone grabbed her and tried to keep her away. People all over the beach were just hugging whoever was close to them or trying to keep any children from witnessing what was going on."
"The damage was too great. We kept his wife away from the body because it was too horrific for her to see."
Chantal Andre, an employee at Anse Lazios beach restaurant, said: I went to the hospital with the mans wife and it was just awful. She wasnt crying at all, she just couldnt believe he was dead.
Jeanne Vargiolu, 56, the owner of Le Chevalier restaurant on the beach, said she saw Mrs Redmond saying she still had hope for her husband while he lay on the beach with horrific injuries.
Ms Vargiolu went to the beach after hearing ambulance sirens to find a French doctor treating the man and a lot of police officers surrounding him. She said the man had lost an arm and flesh from his leg, and had suffered puncture wounds to his chest and stomach.
Ms Vargiolu said the two attacks were the first she had known in the 36 years her family had lived on the beach. "It must be the same shark that attacked 16 days ago," she said.
Police spokesman Jean Toussaint said Mr Redmond was badly injured on the hips and the arms and had lost an arm during the attack.
He was assisted medically but unfortunately he could not make it, Mr Toussaint said. We havent got the autopsy report yet but he definitely lost a lot of blood.
He said Mr Redmond was taken to hospital, but could not be saved. He had no chance of surviving because of the nature of the injuries, he added.
Mr Toussaint said there was a big effort being made to catch the shark.
We had this first incident two weeks ago and for the local community it was a freak incident because it had never been reported before around the islands, Mr Toussaint said.
The most likely candidate for the attack is thought to be the tiger shark, which is found in tropical waters and is particularly common around the central Pacific waters. Growing to over 5 metres, it is a solitary, mostly night-time hunter which preys on seals, smaller sharks and dolphins. Tiger sharks have been responsible for a large proportion of attacks on humans, including that on surfer Bethany Hamilton in which she lost her arm near to her shoulder.
Other species of sharks which attack humans include the great white, the oceanic whitetip and the bull shark.
The British High Commissioner Matthew Forbes flew to the island to comfort the widowed bride last night.
Bill Houghton, the bride's uncle, said: "Gemma is just devastated. They had a perfect wedding. Ian was a fantastic bloke."
The couple's families, David and Coleta Houghton and Stephen and Corinne Redmond, were flying to the resort last night.
The couple, who arrived in the Seychelles on August 14, had been due to leave Praslin on Friday to spend the weekend on the main island of Mahé before flying back to Britain. They had been staying at the four-star La Reserve hotel.
The Foreign Office confirmed last night that a British national had been killed in a shark attack in the Seychelles.
Last night Alain St Ange, the head of the Seychelles tourism board, passed on his sympathy to the dead mans widow and family.
He told the Daily Telegraph: It was a freak accident. We are closing the beaches pending the arrival of experts from South Africa.
Around 19,000 British tourists travel to the Seychelles every year.
Shark attacks on the islands have previously been linked to the fish industry, with the Seychelles hosting the largest tuna canning factory in the world. The dumping of fish waste into coastal waters is thought to lure predators.
