Naomh Mearnóg is a Gaelic Athletic Association club in the parish of Portmarnock, County Dublin, Ireland.

The team wore a black jersey with an amber sash, the colours of which were inspired by the crest of the Jameson family, of whiskey fame, who lived locally.

St. Marnocks were beaten in extra time by St. Margarets in the final of the Swords tournament played on a Monday in August 1930.

As early as 1935, St. Marnocks were unable to field a team against Innisfails, who were back playing again, at Brian Boru Park.

As things worked out they did not break up and Innisfails went on to reach the final of the Dublin Junior Football Championship only to be beaten by St. Pauls by 1–3 to 0–3.

The following September, St. Marnocks beat the reigning Dublin Junior Football Champions, St. Pauls, in the semi-final of the Loving Cup by 1–4 to 0–2.

The greatest achievement of this team was beating Fingallians in the final of 1936 Dublin Junior Football Championship in Parnell Park.

The team that lined out in the Junior Final was: J. McManus, F. Morris, J. Brady, N. Morton, J. Rafferty, J. Connor, F. Donnelly, T. McLernon, M. Reilly, D. Fitzgerald, P. French, T. Tighe, E. Kealy, M. Gilsenan and J. Fogarty.

At the relaunch of the club, chaired by Mr. Leo Nealon, some members of the Dublin panel including Jimmy Keaveney, David Hickey and Robbie Kelleher were present.

Records show that that meeting was attended by Frank McNulty, Patsy Haran (later to become Lord Mayor of Portmarnock), Danny McCormick, Vincent Hughes, Mícheál Ó Braonáin, Jim Carroll, Eugene Keaveney, the Hanley brothers, Tom, Pat and Jack, Pat Keaveney (Principal of St. Marnock's School), Christy Dwyer, Tony Jordan, Pat Dillon and Robert Kenny as well as the five original founding members.

Éanna Mac Cába, as acting Treasurer, reported to the meeting that the club's finances were in a healthy state, showing a credit balance of £27 made up of subscriptions from Jackie Hughes, Brother O’Fearghail (Coláiste Mhuire), Ray Burke T.D.

This first meeting set up a Finance Committee with the following members: Tom Farrelly, Pat Keaveney, Brendan Shannon, Martin McDonagh and Frank McNulty.

A juvenile committee was also set up to organise underage games in the club under the auspices of the following: Frank McNulty, Patsy Haran, Mícheál Ó Braonáin, Pat Keaveney and Christy Dwyer.

[2] The club grounds were officially named "Páirc Mhearnóg" in 2010 to mark the tenth anniversary since the clubhouse was built.