Question:What is the ruling regarding swimming in the sea or in the pool during the day in Ramadan?
A We say (that) there is no harm in the fasting person swimming in the sea or in the pool, whether the pool is deep or otherwise, he can swim as he wishes and immerse himself in the water.
However, he must – to the best of his ability – take care not to allow any water into his stomach.
Swimming energises the fasting person and assists him in his fast; And that which energises (a person) in obedience to Allah, then there is no harm in it because it is from that which reduces the effects of hardship of worship for the worshipper and makes it easy for him.
Allah says in the verses related to fasting:
“…Allah intends for you ease, and He does not want to make things difficult for you. (He wants that you) must complete the same number (of days), and that you must magnify Allah for having guided you…” [Qur’an, 2:185]
And the Prophet ﷺ said: “This religion is easy. No one becomes harsh and strict in the religion without it overwhelming him.” [Bukhari and Muslim]
So there is no harm in swimming in the pool, just as there is no harm in taking a shower and other than that; And Allah has the Complete Knowledge (of all affairs).
– Sheikh Ibn ‘Uthaymeen, Fatawa Ramadan – Volume 2, Page 524, Fatwa No.490, Fatawa Ibn ‘Uthaymeen – Volume 1, Pages 509-510