Objective: Hyperbaric oxygen therapy (HBOT) is the most crucial treatment for decompression sickness (DCS), which needs to be administered as swiftly as possible. This study evaluates the therapeutic responses of DCS patients and analyzes the major factors for clinical outcomes. Methods: This is a retrospective cohort single-center study on patients who arrived at our hospital’s emergency department for diving-related symptoms and were diagnosed with DCS and administered HBOT. Results: Totally, 337 patients were enrolled from June 2015 to May 2020. The proportion of SCUBA diving, rapid ascent, and inter-facility transport cases was higher in the recreational group, with a longer lag time from symptom onset to HBOT. The professional group had a higher proportion of cases with previous DCS history, total diving time, bottom time, in-water decompression, and repetitive diving. Examination of treatment outcomes revealed more type I cases and a shorter lag time from symptom onset to HBOT in the complete recovery group. Conversely, the incomplete recovery group had a higher proportion of type II cases and aggravation of symptoms before HBOT was administered. Conclusion DCS can occur regardless of professional or recreational divers. Both groups showed a similar level of severity. It is recommended that recreational divers should be cautious of accidents related to safety (such as rapid ascent) and receive swift treatment in case of the onset of symptoms. Occupational divers need more active efforts to get HBOT rather than just performing in-water recompression or home O2 therapy.