The song is Eanach Dhúin (although in the recently-published Leabhar Mór na nAmhrán [Cló Iar-Chonnacht] it is called Eanach Cuain) after the place name where the disaster took place. As a child I heard more verses of it than have appeared on this thread, including this one: Ansiúd Dé hAoine, 'sea chluinfeá an caoineadh Ag teacht ó ghach taobh díot is an greadadh bos; is a lán thar oíche, trom tuirseach cloíte, Gan ceo le déanamh acu ach ag síneadh coirp. A Dhia is a Chríosta, d'fhulaing íobairt a cheannaigh go fíreannach an bocht is an nocht, Go Párthas naofa, go dtugair saor leat gach créatúr díobh dar thuit faoin lot.
I remembered only the the first four lines of that verse but the rest I got from the above-mentioned book, which also give three other vereses.