Pebbles at Riwon are distributed on the shore of the East Sea of Korea off the Rahung Workers’ District in Riwon County of South Hamgyong Province.
The arch-shaped beach is 800 metres in length and about 30 metres in width.
Lumps of weathered quartzite fell down there and have been worn by waves to form white and creamy oval pebbles, big and small.
The stones are 2 to 30 cm in diameter, and the biggest is 33cm.
As natural pebbles rare to be found around the world, they are under protection as a natural monument for their beautiful scenery and academic significance.