The Vinh Moc tunnels on the coast just north of the old border between South and North Vietnam were dug by the Viet Cong as a staging ground for forays into the Demilitarized Zone and to protect part of the supply line known as the Ho Chi Minh Trail. These damp tunnels have many small alcoves and once housed 200 people. 17 babies were born down here in the 'maternity room'.