下龙市（越南语：Thành phố Hạ Long），原名鸿基市社（越南语：Thị xã Hòn Gai和Hồng Gai／.mw-parser-output .han-nom{font-family:"Nom Na Tong","Han-Nom Gothic","Han-Nom Ming","HAN NOM A","HAN NOM B","Ming-Lt-HKSCS-UNI-H","Ming-Lt-HKSCS-ExtB","FZKaiT-Extended","FZKaiT-Extended(SIP)","FZKaiS-Extended","FZKaiS-Extended(SIP)","Sun-ExtA","Sun-ExtB","MingLiU","MingLiU-ExtB","MingLiU_HKSCS","MingLiU_HKSCS-ExtB","SimSun","SimSun-ExtB",sans-serif} 市社丸荄），是越南东北部广宁省的省莅，位于河内市以东178公里。附近的海上有著名风景区、世界自然遗产下龙湾。

下龙市东接锦普市，西接汪秘市和广安市社，北接