The teenagers, named locally as Reuven Simon and Joseph Sebastian, had been swimming at Lough Enagh on Monday evening when the tragic scenes unfolded.
The boys had been in a larger group who stopped off at the lough while cycling in the area.
They were pupils at St Columb’s College in the city.
The bicycles the boys had been riding remained beside the lough on Tuesday which has been cordoned off by police, while some locals visited the small jetty to leave flowers in tribute.
Principal Finbar Madden described “shock and sadness” within the school at the “heart-breaking loss of two of our incoming Year 13 pupils”.
“No words can express the devastation that we feel as a school community, but first and foremost our thoughts and prayers are with both boys’ families, community and friends,” he said in a statement.
“This will be a very difficult time for the whole St Columb’s family and in the coming days it will be important that our pupils are with people they know and trust.”
He said they will be providing support for the students and the school would be open on Tuesday afternoon for any pupil who wanted to spend time with staffn and friends>
The boys had been involved with Newbuildings Cricket Club.
In a statement, the club described them as “two of the most well mannered and lovely people”.
“It was an absolute pleasure to have in our U15s last season,” they said.
“Our thoughts and prayers go out to their families & friends, survivors and the wider Kerala community.”