There is a large yellow building that overlooks Ballinskelligs strand in Co Kerry, at an enviable location on the far end of the beach. It sits back from the strand at a height, the lawn ending in a drop that’s protected from erosion by a concrete wall at its base. Anyone familiar with Ballinskelligs will know this building, distinctive by the cross that rises from its flat roof.

St Michael's in Ballinskelligs is the purpose-built holiday residence of the Presentation Sisters' order, dating from 1939. In an era when numbers in the religious community were far higher than today, most orders had designated holiday houses on the coast, with Clare, Waterford and Kerry being most favoured. At the opposite end of the beach from St Michael's, there is a holiday house owned by the Sisters of Mercy.

St Michael's is where my great aunt, Bridget Kennelly, known as Sr Kevin by her community and Auntie Bride by her family, came on holiday each summer. She was born in 1900, and entered the convent in 1923. I have only one clear memory of her. It is of attending her 50th Jubilee celebrations as a Presentation Sister in Castleisland, Co Kerry when I was a child. Being alive for 50 years seemed incredible enough to me then, let alone being a nun for five decades. She was 94 when she died, having spent a total of 71 years as a nun.

Although the religious community in Ireland has contracted greatly since 1939, the Presentation Sisters continue the tradition of holidaying here each summer. They arrive at the beginning of July, with the first week spent in retreat, and depart on 15th August. During that period, sisters from different parts of the country come to stay for varying lengths of time.

One sister, the Superior, remains in residence for the entire six weeks to oversee the day-to-day running of the house. For several years now, it has been Sr Eileen Leen, who entered religious life in 1956. "I don't know how you'd describe me. Am I in charge? I suppose I am," she says briskly.

The large site was bought in 1938 for £50; the following year, when the house first opened, the dormitory accommodated 64. It was full all summer, and those who filled it were only the Kerry-based nuns. In 1988, the house was refurbished and the dormitory converted into 20 single bedrooms. Bathrooms remain communal.

On the cerulean blue July day that I visit, there are four nuns on holiday, and six more are expected the next day. “There’ll be a few young ones among them,” Sr Eileen says. When pressed on what ‘young’ means, she answers, “late 60s”.

The other three nuns currently on holiday are Sr Borgia Shanahan, Sr Regina O'Connell, and Sr Anne Roche. Between the four of them, they have spent a cumulative 245 years in the convent.

We are having lunch in the refectory, a large, sunny room with gorgeous views out over Ballinskelligs beach and bay. It once held eight long wooden tables, each seating eight. Now a few small round tables suffice. The rest of the space is occupied by bookshelves, and antimacassared armchairs that face a fireplace and a television.

Over cauliflower cheese, mashed carrots, new potatoes and beef, followed by stewed rhubarb and ice-cream, the nuns reminisce about former holidays. They were allowed three weeks at Ballinskelligs during the summer. They all remember the pre-Vatican II habits they wore, even on the hottest days. "Six yards of serge and a wimple," Sr Eileen recalls grimly.

'Nearly fainting'
"We walked for miles in them in the fields and up mountains. You'd nearly be fainting at the end of it," says Sr Regina. Today, only Sr Borgia (93) is wearing a habit, and it's a modern one.

The nuns had to obey rules set down by the Kerry Bishop of the day, Bishop Michael O'Brien. These were pinned up inside the house, and nicknamed by the community as "the Ten Commandments". The nuns were forbidden to speak to people on the beach; wear 'modern swimsuits' (above elbow and knee); go to the local shop without permission; go swimming more than once a day; go alone on the rocks; go for long walks in the afternoon, unless as part of a group, following a leader. They also had to speak Irish as much as possible and observe set periods of silence.

It sounds, frankly, not like a holiday at all, and impossible to imagine any group of adults obeying rules like these today. Yet their annual three weeks by the sea were cherished each year, as they still are.

Sr Eileen has been thoughtful enough to search through their archive in advance of my visit and find photographs of my great aunt. She also shows me documents from their archive by a nun, now dead, who wrote down memories of her holidays.

In 1989, Sr Gonzaga O'Keefe wrote about the summer the house first opened, half a century previously. Then as now, the beach was bisected by a small river, known as the "Black Pipe". After a celebratory Mass on the day the house opened, Bishop O'Brien took the nuns for a walk on the beach. "We gathered round him like clucking hens," Sr Gonzaga wrote.

The bishop “pointed to the ‘Black Pipe’ on the strand and said, ‘Thus far and no farther’. We were also told that boating was not for us, and walks on the road were out. We may laugh at this now, but we accepted it without protest then, so glad were we to have the holiday and a measure of freedom.”

That first summer, the building and plumbing work had not been completed when the nuns moved in. A donkey cartload of “much chipped and somewhat rusty chamber pots” arrived, to be placed at “strategic points” in the dormitories.

"There was no electricity the first few years," Sr Regina says. "We used candles. Lights out were at 10 o'clock." When they were not practising their Irish, knitting on the lawn, having their one allocated swim a day, or out walking the mountains in six yards of black serge, they gathered on the rocks at the end of the beach for sing-songs. "We used to have great fun. We'd sing things like The Hills of Donegal. Or we'd do little sketches."

Inside I'm dancing
Sr Eileen shows me the sanctuary room, where the nuns heard Mass every morning. It's as big as the refectory, and behind folding wooden doors, is the tabernacle. "We would close the doors here in the night, out of respect," she explains, "and then sometimes sisters who had relatives nearby, would come in and play the accordion or sing, and we'd dance." She recalls two nuns who were actual sisters, and whose father came every summer to play the accordion for their community.

“We danced ballroom, quickstep, foxtrot, waltzes. Before we entered, we’d have been going to the dances on our bicycles, so we knew them all. We’d usually have a little party after dancing on the nights we were dancing: lemonade and biscuits. Red lemonade. Nash’s red lemonade was the best thing for a cold; You’d boil it up and put a few cloves in it.”

There's no dancing at St Michael's any more, but the sisters still enjoy themselves. As they are on holiday, they don't cook: someone is employed to do it. "We light the fire on misty nights and play Scrabble," says Sr Eileen. They watch television: their favourite programmes are Nationwide – "It always gives your heart a lift," as Sr Regina says – and anything to do with nature. They read. They walk where they like. Sr Borgia naps each afternoon. They are content and self-contained, and fewer in number each year.

When I have said my goodbyes, I go for a swim at the beach below, and think about the life my great aunt led. After a while, someone comes down the private steps from the nuns’ garden. It is Sr Eileen, in a modern swimsuit, pausing on her way to the warm water to chat to people she evidently knows. If it had been 1939, she would have been breaking two of the “Ten Commandments” in under a minute.