Stella Kambi, 17, died after going into the water at Thorpe Marshes nature reserve near Norwich to try to save Bonheur Musungay, 14, on 12 August.
An inquest, which was opened and adjourned in Norwich, heard that a number of people tried to find them without success.
Post-mortem examinations confirmed the teenagers both drowned.
At the brief hearing, Norfolk assistant coroner Johanna Thompson said both Stella and Bonheur were in a group of adults and children at the former quarry.
She said at about 16:40 BST Bonheur was in the water when he began to get into difficulties.
Stella jumped into the water to try and help him but then got into trouble herself, the inquest heard.
Onlookers said they saw the pair disappear under the water.
Their bodies were eventually found by fire crews at about 19:40 BST.
A full inquest will be held in March next year.
Members of the public went into a lake to try and find two teenagers who drowned, an inquest has heard.