Local residents raised the alarm after watching as Ms Sriwan took a motorbike taxi to the pier, walked to the end and jumped off at about 8:30am.
Fishermen in a longtail boat and a speedboat were dispatched to search for her, and found her body two hours later around the small cape to the east of the pier, at Laem Ka Yai.
Officers from Rawai Municipality, along with Rawai Mayor Aroon Solos were soon at the scene, as were first-responders from Khaimook Rescue, who transported her body to Vachira Hospital in Phuket Town.
Ms Sriwan apparently worked at a spa in Wichit. She was found with 180 baht and one motorbike key in her pockets.
Chalong Police are continuing their investigation into her death.