In Hinduism, there is importance of taking bath before doing rituals, and an important part of ritual purification in Hinduism is the bathing of the entire body.
It is considered auspicious to perform this form of purification before any festival, before visiting a temple or performing a worship. One not only purifies one's body but also the mind during taking a bath.
Below is one famous shloka that I am aware of, typically used while taking a bath
गङ्गेच यमुने चैव गोदावरी सरस्वति । नर्मदा सिन्धु कावेरी जलेऽस्मिन् संनिधिं कुरु ॥
Meaning: In this water, I invoke the presence of divine waters from the rivers Ganga, Yamuna, Godavari, Saraswati, Narmada, Sindhu and Kaveri. These rivers are considered as goddesses and I pray to them for considering me for their blessings.
Are there any other similar shloka/mantra recommended in Hindu scriptures which one can chant when taking a bath?