<jats:title>Abstract</jats:title><jats:p>Two new alkene sulfates, (5<jats:italic>Z</jats:italic>)‐dec‐5‐en‐1‐yl sulfate (<jats:bold>4</jats:bold>) and (3<jats:italic>E</jats:italic>)‐dec‐3‐en‐1‐yl sulfate (<jats:bold>5</jats:bold>), together with three known sulfated alkanes, 2,6‐dimethylheptyl sulfate (<jats:bold>1</jats:bold>), octyl sulfate (<jats:bold>2</jats:bold>), and decyl sulfate (<jats:bold>3</jats:bold>), were isolated from the sea cucumber <jats:italic>Apostichopus japonicus.</jats:italic> The structures of the new compounds <jats:bold>4</jats:bold> and <jats:bold>5</jats:bold> were elucidated by spectroscopic analysis, including <jats:sup>1</jats:sup>H‐, <jats:sup>13</jats:sup>C‐, and 2D‐NMR, ESI‐MS, and HR‐ESI‐MS. Compounds <jats:bold>2</jats:bold> and <jats:bold>3</jats:bold> were isolated from natural sources for the first time. In preliminary bioassays <jats:italic>in vitro</jats:italic>, compounds <jats:bold>4</jats:bold> and <jats:bold>5</jats:bold> showed antibacterial, antifungal, and cytotoxic activities.