Aquatics at the 1983 Southeast Asian Games included swimming, diving and water polo events. The three sports of aquatics were held at Toa Payoh Swimming Complex, Singapore City, Singapore. Aquatics events was held between 29 May to 3 June.
| 100 m freestyle |  Ang Peng Siong | 53.58 (rec) | Tay Khoon Hean | 54.45 |  Lukman Niode | 54.63 |
| 200 m freestyle |  William Wilson | 1:57.97 (rec) | Lukman Niode | 1:58.18 | Tay Khoon Hean | 1:59.32 |
| 400 m freestyle | William Wilson | 4:08.94 (rec) | Soo-Tho Kok Mun | 4:16.38 | Joselito Andaya | 4:18.24 |
| 1500 m freestyle | Joselito Andaya | 16:50.69 | Soo-Tho Kok Mun | 17:11.39 | William Wilson | 17:38.00 |
| 100 m backstroke | Lukman Niode | 59.72 (rec) | David Lim | 1:01.54 | Judy Jaoud | 1:03.97 |
| 200 m backstroke | Lukman Niode | 2:13.41 (rec) | David Lim | 2:14.80 | Judy Jaoud | 2:19.80 |
| 100 m breaststroke | Jairulla Jaitulla | 1:08.10 (rec) | Francisco Guanco | 1:09.56 | Oon Jin Teik | 1:10.17 |
| 200 m breaststroke | Francisco Guanco | 2:29.46 (rec) | Tjatur Sugiarto | 2:33.33 | Rene Concepcion | 2:34.33 |
| 100 m butterfly | Ang Peng Siong | 57.87 (rec) | Tay Khoon Hean | 59.52 | John Item | 60.34 |
| 200 m butterfly | William Wilson | 2:10.07 | Ridwan Muis | 2:12.14 | Renato Padronia | 2:13.67 |
| 400 m individual medley | William Wilson | 4:45.72 (rec) | Jairulla Jaitulla | 4:50.66 | Soo-Tho Kok Mun | 4:56.81 |
| 4x100 m freestlye relay | 3:38.42 (rec) | 3:43.42 | 3:47.85 | |||
| 4x100 m medley relay | 4:02.64 (rec) | 4:03.62 | 4:09.81 | |||
| 4x200 m freestlye relay | 8:06.32 (rec) | 8:06.81 | 8:13.03 | |||
| 100 m freestyle | Junie Sng | 1:01.77 | Chan Mui Pin | 1:02.13 |  Helen Chow | 1:02.57 | |
| 200 m freestyle | Junie Sng | 2:10.31 | May Tan | 2:13.36 | Chan Mui Pin | 2:13.51 | |
| 400 m freestyle | Junie Sng | 4:29.74 (rec) | Elfira Rosa Nasution | 4:38.75 | Chan Mui Pin | 4:39.28 | |
| 800 m freestyle | Junie Sng | 8:59.46 (rec) | Katerina Ong | 9:33.92 | Elfira Rosa Nasution | 9:34.70 | |
| 100 m backstroke | Christine Jacob | 1:10.34 | Kwek Leng | 1:10.78 | Lai May May | 1:10.95 | |
| 200 m backstroke | Christine Jacob | 2:29.00 (rec) | Kwek Leng | 2:32.81 | Helen Chow | 2:34.82 | |
| 100 m breaststroke | Helen Chow | 1:18.88 | Ee Yan Hui | 1:19.72 | Lourdes Samson | 1:20.01 | |
| 200 m breaststroke |  Kanogwan Sriprasert | 2:25.17 | Christina Tham | 2:56.93 | Sandra Melani Maksudi | 2:57.35 | |
| 100 m buttertfly | Junie Sng | 1:05.32 (rec) | Helen Chow | 1:06.40 | May Tan | 1:06.86 | |
| 200 m butterfly | Junie Sng | 2:20.35 (rec) | Mavis Ee | 2:24.54 | Selowati Hadi Sujono | 2:28.22 | |
| 400 m butterfly | Junie Sng | 4:29.74 (rec) | Elfira Rosa Nasution | 4:38.75 | Katerina Ong | 4:39.28 | |
| 400 m individual medley | Junie Sng | 5:04.37 (rec) | Elfira Rosa Nasution | 5:30.11 | Pasawan Phantumabumroong | 5:38.97 | |
| 4x100 m freestlye relay | 4:11.21 (rec) | Philippines Thailand | 4:15.29 | ||||
| 4x100 m medley relay | 4:39.12 (rec) | 4:41.84 | 4:46.89 | ||||
| Men's | Singapore | Malaysia | Indonesia |
| Men's springboard | Kristiadi Permana | 490.85 | Sangwal Foungdee | 454.70 | Haryo Ramayana | 398.45 | |
| Men's placing | Somchai Ongkasing Ong Ka Sing | 158.25 | Leong Siet Fong | 156.35 | Richard Tham | 155.85 | |
| Men's platform diving | Somchai Ongkasing | 453.55 | Eko Setiadi | 440.65 | Richard Tham | 415.60 | |
| Women's springboard | Indah Siantiningsih | 308.80 | Dwi Setyowati | 294.86 | |||
| Women's placing | Indah Siantiningsih | 167 | Dwi Setyowati | 166 | Lee Po Ling | 159.45 | |
| Women's springboard diving | Indah Siantiningsih | 373 | Dwi Setyowati | 331.50 | Lee Po Ling | 322 |