Krabi's mountainous physical geography is broken by highlands and plains on the mainland.The provincial administration also covers more than 130 islands in the Andaman Sea. Natural forest cover is chiefly mangrove and Cassia trees. Krabi's sandy clay soil conditions are perfect for a variety of agricultural products, including rubber trees, palms, mangos, coconuts, and coffee. The Krabi River flows 5 kilometers through the city and falls into the Andaman at Tambon Pak Nam. There are other streams as well : the Khlong Pakasai, the Khlong Krabi Yai and the Khlong Krabi Noi in the province's highest range of mountains, the Khao Phanom Bencha.