Several parts combine into one character.

泳 is a phonetic-semantic compound: 氵 (water radical) plus 永 (long / lasting). The composite reads as "to move through water for a long time" — to swim. The connection is doubly meaningful: 永 itself originally depicted long, branching streams of flowing water, so the etymology of 泳 contains water twice over, once as the radical and once as the phonetic/semantic component.

Korean reading "yeong." Limited to swimming-related compounds: 水泳 (suyeong, swimming), 泳法 (yeongbeop, swimming stroke / technique), 背泳 (baeyeong, backstroke), 平泳 (pyeongyeong, breaststroke). 泳 never appears as a standalone Korean word.

Mandarin yǒng, 3rd tone. The standard Chinese word for swimming is the two-character compound 游泳 (yóuyǒng) — combining 游 (to drift / float / wander through water) with 泳 (to swim). Both characters mean swimming-related motion, and Chinese typically requires both to form the noun. Other compounds: 泳衣 (yǒngyī, swimsuit), 泳池 (yǒngchí, swimming pool), 蛙泳 (wāyǒng, "frog swim" = breaststroke).

Japanese on-reading エイ (ei) appears in formal compounds: 水泳 (suiei, swimming), 背泳 (haiei, backstroke), 競泳 (kyōei, competitive swimming). Kun-reading およぐ (oyogu, to swim) — 泳ぐ is the everyday verb. The metaphorical extension 世間を泳ぐ ("to swim through society") means "to navigate the social world skillfully" — a very Japanese metaphor for managing relationships.

Memory aid: water (氵) + lasting (永) — sustained motion through water.