CC Antya 18.28

yamunāra bhrame prabhu dhāñā calilā
alakṣite yāi’ sindhu-jale jhāṅpa dilā
Word for word: 
yamunāra bhrame — by mistaking for the Yamunā; prabhu — Śrī Caitanya Mahāprabhu; dhāñā calilā — began to run very swiftly; alakṣite — without being seen; yāi’ — going; sindhu-jale — into the water of the sea; jhāṅpa dilā — He jumped.
Translation: 
Mistaking the sea for the Yamunā, the Lord ran swiftly and jumped into the water, unseen by the others.