Mahabharata 18.3.4

नादृश्यन्त च तास्तत्र यातनाः पापकर्मिणाम्नदी वैतरणी चैव कूटशाल्मलिना सह

nādṛśyanta ca tāstatra yātanāḥ pāpakarmiṇāmnadī vaitaraṇī caiva kūṭaśālmalinā saha

Our plain-language meaning of this verse is waiting for scholar review.