Jukdo is located 4 km northeast of Jeodong port and 7 km away from Dodong port. The largest of the 44 islets (4 inhabited islets, 40 uninhabited islets) annexed to Ullueng-do, Jukdo is as large as 207,868㎡. The island is covered with a thin layer of pumice. The island is called Jukdo, Daetsom, or Daenamuseom for its dense groves of self sustaining bamboo trees. The cliffs are composed of oddly shaped rocks. Jukdo is mainly composed of trachytic lava flows and tafoni (honeycomb weathering in rock) are well-developed on the vertical coastal cliffs. Although the island was initially attached to Ullueng-do, it was separated from the main island by wave erosion. The substructure of Jukdo, similar to that of Ullueng-do, consists of trachyte and basaltic agglomerate. The composition of rocks support this theory. Jukdo is covered with a layer of pumice. Formed during explosive volcanic eruptions, pumice is an extremely porous rock that is light enough to float on water. Deodeok (Codonopsis lanceolata), a specialty produce of Jukdo, is cultivated on the soil, derived largely from weathered pumice. Because pumice soil accelerates water drainage, fresh water supply is generally from Ullueng-do and rainwater is stored for agricultural use.