Nymphs return - so do I, on LA beach or on regular vacation (8)

'nymphs' is the definition.
(I know this)

'return so do i on la beach or on regular vacation' is the wordplay.
'return' shows that the letters should be reversed in order.
'so do i' becomes 'sdi' (this might be a standard abbreviation I've not previously seen).
'on regular vacation' means one should take alternating letters (letters removed or vacated at regular intervals).
'on'+'la'+'beach'+'or'='onlabeachor'
The alternate letters of 'onlabeachor' are 'naeco'.
'sdi'+'naeco'='sdinaeco'
'sdinaeco' reversed gives 'OCEANIDS'.