1To jump or dive into something (e.g., water) with force; figuratively, to boldly plunge into a new challenge.
子供たちがプールに次々と飛び込んだ。
The children jumped into the pool one after another.
彼は迷わず起業の世界に飛び込んだ。
He didn't hesitate to plunge into the world of entrepreneurship.
海に飛び込んで泳ぐのが夏の楽しみだ。
Diving into the sea and swimming is one of the joys of summer.
電車に飛び込むのは絶対にやめてください。
Please never jump in front of a train.
2To burst or barge suddenly into a room or place.
ノックもせずに部屋に飛び込んできた。
He barged into the room without even knocking.
ニュース速報が突然、番組に飛び込んできた。
A breaking news bulletin suddenly cut into the program.