At least 10 children died on Sunday and nine are missing after their boat capsized in a dam in north-western Pakistan.
Four others are in a critical condition, local police officials told Pakistani media.
The children were pupils of a religious school and were on a day trip to Tanda Dam in Khyber Pakhtunkhwa province.
All those on-board were between 12 and 20 years old. The 10 known to have died were between seven and 12 years old, deputy district commissioner Furqat Khan told Reuters.
A rescue operation is still under way at the lake.
The dam had been closed to recreational tours after previous accidents, Mr Khan said.
Transport accidents are not uncommon in Pakistan, where poor infrastructure and lax safety measures are rife.
At least 18 women drowned in July when a boat carrying a wedding party capsized in Punjab province.
The boat was carrying more than 100 people and capsized due to overcrowding and high water levels, officials said.
The latest accident comes on the day that a bus crash killed 40 in the south of the country.
The passenger bus, travelling from Quetta to Karachi, was speeding and fell into a ravine before catching fire, a local official said, leaving many of the victims burnt beyond recognition.
Authorities said the driver may have fallen asleep.
In November, 20 people, including 11 children, were killed when a minibus crashed into a deep and waterlogged ditch in the south of the country.
Many passenger buses are often overcrowded and lack basic safety measures, including seat belts.
