Notable experience swimming so deep around island (7)
I believe the answer is:
episode
'notable experience' is the definition.
'episode' can be an answer for 'experience' (thesaurus). I'm unsure of the 'notable' bit.
'swimming so deep around island' is the wordplay.
'swimming' indicates anagramming the letters (letters swim around into a new order).
'around' means one lot of letters goes inside another.
'island' becomes 'i' (geographical abbreviation).
'so'+'deep'='sodeep'
'sodeep' is an anagram of 'epsode'.
'epsode' enclosing 'i' is 'EPISODE'.
Can you help me to learn more?
(Other definitions for episode that I've seen before include "Part of TV series" , "Instalment of a TV series" , "Chapter or event" , "One instalment of a series" , "Instalment; incident" .)