Kevin O'Hare, 15, got into trouble while swimming at the quarry in Annalong on Saturday evening.
Colin Polland, 39, also died when he tried to rescue the teenager at Paul's Quarry in the Glassdrumman Road area.
Their funerals were held separately in Co Down on Wednesday.
Pupils at St Michael's Primary School and high school, and members of Dromara GAA club were among the hundreds to attend Kevin's funeral.
As his coffin was borne into St Michael's Church in Finnis, one of the pallbearers was Kevin's father, followed by his three brothers, and his distraught mother.
Father Peter McNeill told the hundreds of mourners, many of whom had to stand outside, that Kevin was "so loved and so loving".
He paid tribute to the rising GAA star, saying there was something about Kevin which touched the lives of others.
At St Patrick's Church in Bryansford, Mr Polland was described as a good son, husband, and father, with a strong interest in music and genealogy.
Speaking Father John Cunningham said: "Colin or, as his friends would call him, CP was always positive and always smiling, he had an infectious personality and a mischievous grin.
"He was always happiest when he was with Adele. He loved catching up with his friends, many of which were life-long friends.
The priest paid tribute to Mr Polland's bravery in trying to rescue Kevin, adding: "Both Colin and Kevin can now call each other friends in the up above they now share."