The organisers of Sunday's papal mass in the Phoenix Park have released a list of prohibited items.
Large umbrellas and deckchairs are among the many items included on the list.
Banners of any size, flags, flagpoles, placards and posters are also banned from the event.
Selfie sticks and drones are also prohibited, as are excessive amounts of batteries, wires, cables or electrical components.
Alcohol, glass bottles and cans cannot be brought to the event.
As the event is not seated, many people are planning to bring their own chairs. While this is allowed, particular seats are not allowed including deckchairs, garden furniture, blow up furniture, folding armchairs and shooting sticks stools.
Mobility scooters, large prams and bicycles are prohibited, as are crash helmets, protective headwear and protective clothing.
Registered guide dogs are the only animals allowed in to the Phoenix Park on Sunday.
Camping and cooking equipment are prohibited, as are cooler boxes and large containers.
Other prohibited items include air horns, fireworks and flares, laser/laser pens, smoke cannisters, sound systems, spray cans, large chains, spiked bracelets or wallet chains any item which may reasonably be considered for use as a weapon.
Illegal merchandise and illegal substances are also prohibited.
The day will involve lengthy walks to and from the mass, so people are encouraged to wear comfortable shoes.
There will be designated rest zones at regular intervals at the transport hubs, along the walking routes and at the gates to the park, the organisers say.
Food and drink stations will be available, toilets, baby changing facilities and medical facilities.
To prepare for all weather possibilities, people are advised to bring a light jacket and warm clothes.
Hand sanitiser, a small folding chair, backpack, suncream and a bottle of water might also be useful on the day.
