Police said Boobesh Palani died at Wellington Hospital surrounded by his friends.
Palani, who was studying in New Zealand, was rescued from the water at Burdan's Gate, Eastbourne, on Monday by two teenage girls and two young men.
Palani's identity was initially unknown. But a person identified him after seeing his photo on New Zealand news websites, New Zealand Herald reported.
Cousins Kelly McKay 15, and Payge Olds, 16, were with a groups of friends when they heard that Palani was in trouble.
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When she reached Palani he was completely submerged.
When Palani was eventually pulled to shore, Kelly performed CPR before emergency services arrived.
Palani's family thanked the public for their support over the last few days.