The Marble Mountains are a towering cluster of five marble and limestone hills in Hoi An, named after the five elements Kim, Hoa, Thuy, Tho and Moc. Acclaimed as one of Vietnam's top natural treasures, these porous limestone peaks are punctuated by caves and tunnels, sheltering spectacular Buddhist grottos and Hindu shrines established by the Cham people. Of the five, Mount Thuy is accessible to tourists via trekking and overlooks jaw-dropping views of Da Nang city and the coast.