およぎだしたそうだ
oyogidashita sōda

Godan Verb (su)
Evidential Auxiliary

Expresses hearsay about a past event ("I heard that...") of 泳ぎだす

1. They say (he/she/it) started swimming.; It is said (he/she/it) began to swim.

Past/Perfective
Hearsay Evidence