The group took turns to swim the equivalent of 22 miles — the distance from Dover to Calais — at the popular pool within a specific time limit.
The swimmers attend regular physiotherapy sessions, held by Jan Bruce, and decided to club together to raise money for Aspire — a charity which helps people with spinal injuries.
The swimmers actually finished the mammoth swim early, and Eastbourne mayor Greg Szanto visited the pool to congratulate them.
A group spokesperson said, "This is good for the morale of those of us who are in various stages of disarray recovering from accidents, joint replacement operations, or are disabled.
"We're not a formal group, having loosely banded together for this fundraiser, but we have in common much appreciation of what Jan's rehab sessions do for our health and realise that not everyone is as lucky as we are to have a Motcombe Pool or its equivalent."
Jan, the group's physiotherapist who began the rehab sessions, is disabled but joined in the 2,000 lengths required to complete the challenge.