The story
From the Hanyu Pinyin romanization of Mandarin 杭州 (Hángzhōu), from its former role as the seat of Hang Prefecture (also 杭州 (Hángzhōu)), folk etymologized as a reference to King Yu's ferry over the Qiantang on his way to Shaoxing but more likely a transliteration of an earlier Baiyue placename.
Etymology from Wiktionary, CC BY-SA 4.0.