On Thursday (June 25), a woman was taken to hospital with cuts and bruises to her face after being assaulted just west of the Sea Lane Café in Marine Drive.
Sussex Police said the altercation was between two women at around 3.30pm.
The other woman, aged 35, was arrested on suspicion of grievious bodily harm and ha sbeen released under investigation, police said.
Police are keen to hear from anyone who witnessed the incident, or who may have any relevant camera phone or dash cam footage to get in touch.
Anyone with any information is asked to contact police online or by calling 101 quoting serial 1025 of 25/06.