Valmiki Ramayana Sundara Kanda Sarga 1 Shloka 50

अथ and then, सारवन्तः huge, ये those, वृक्षाः trees, महेन्द्रस्य Indra's, भयात् out of fear, पर्वताः mountains, वरुणालये इव like the abode of Varuna, ocean, लवणाम्भसि in the salt sea, न्यमज्जन् sank.

Then the huge trees sank into the ocean of salt water even as mountains did, afraid of Indra's (thunderbolt).