A North Korean soldier and another boat passenger told the South's military they wanted to defect, the Yonhap news agency said citing a government source.
The defectors reportedly navigated their boat to the Baengnyeong Island in the Yellow Sea near the inter-Korean maritime border.
This is the first escape from North Korea since the leaders of the two countries met for rare talks on the border in late April. They agreed to sign a peace agreement later this year and aim for a peaceful reunification. Previous year, a 24-year-old soldier, Oh Chung-sung, fled across the border to the South under fire.