横渡 specifically means crossing a body of water from one shore to the other (across the current/width), as opposed to
渡过 (dùguò, just 'to cross'). It's the canonical word for swimming or sailing across rivers, channels, and straits. Mao Zedong's symbolic 1966
横渡长江 swim across the Yangtze became one of the iconic political-propaganda moments of the era — and made the word a signature feat of athletic willpower in Chinese.
