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Geological and Geomorphologic Setting

The Portuguese Central region between Rio Maior, Alcobaça, Porto de Mós, Batalha, Leiria, Ourém, Torres Novas and Alcanena is occupied by Limestone Mountains, which form the Estremadura Limestone Massif. Of these the mains mountains are the Aire and Candeeiros.

This region is characterized for not being crossed by any rivers, since rainwater sips almost completely through the cracks in the rocks instead of streaming down the slopes to create rivers. Unlike other rocks limestone is dissolved by water, which sculpts curious formations, small sinks and pots, ridges and high pedestals. These are called limestone pavement by the scientists that study them and are classified according to their origin, shape and dimensions.

Another trace of limestone regions is the existence of closed depressions with rocky slopes and the bottom covered by red clayish soils. In the region theses depressions are known as ?covões? and the soil as ?Felgar?. Scientists call the depressions sinkholes and terra rossa to these soil which are characteristic of all limestone regions across the Mediterranean.

Unlike limestone pavements, of naked rock that only goats dare to cross, sinkholes are the rare locations where agriculture is possible, corn, potatoes and other species that don?t demand a lot of water are the preferred cultures. However with some ingenuity and effort, man spread wherever it could thousands of olive trees taking advantage of the smallest bits of soil.

Where the soil was scarce, it was necessary to dig out rocks which were set as walls also very typical of limestone regions.

By penetrating the fissures of the rocks, water expands them by dissolution and transforms them in large corridors or in natural well, which are known as pit cave.

It was on one of these pit caves existing on the place called ?Moinhos Velhos? (old windmills), a very small one at that, and apparently like so many other that in 1947 some inhabitants of Mira de Aire entered and thus discovered the cave.

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Geological and Geomorphologic Setting

Cave Formation

Water on its endless cycle, absorbs large quantities of carbon dioxide as it condensates in the atmosphere to fall down again as rainwater.

In limestone areas when it rains, the rainwater will spread across the fields and sink into the cracks in limestone enlarging them by natural mechanic erosion and by the chemical reaction caused by carbon dioxide.

Limestone is formed mostly by calcium carbonate, which is dissolved by carbon dioxide saturated waters and originating calcium bicarbonate, and so becomes a soluble substance.

In its permeabilization process, as these waters reach the cave void, they create small drops that upon their release from the caves ceiling create all types of formations.

A part of these waters will naturally be evaporated, and thus diminishing substantially the amount of carbon dioxide initially existing. This operation will create and opposite chemical reaction, which means calcium bicarbonate will become calcium carbonate once again, and because this is solid it will hang from ceilings in cone shapes slowly growing throughout the ages under the name of stalactites. However if the drops fall at a regular cadency the chemical phenomenon can create formations from the ground which are known as stalagmites. Both formations can be joined as columns of astounding effects.

In the ceilings, because of narrow and long fissures through which water can drip during its permeabilization, great drapes of thin crystal filaments frequently grow using the same process described before.

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Extension
TICKET OFFICE HOURS

From October to March - from 9:30 am to 5:00 pm
April, May and September - from 9:30 am to 6:00 pm
June to August - from 9:30 am to 6:30 pm
January 1st - 10am to 5pm

OPEN DAILY

Including weekends and holidays with the exception of December 25th

Total length of the cave: 11km

Extansion

Information about
visits

Visits

It’s not necessary to book a tour in order to visit the cave unless you have group with more than 20 adults or a school group. More information on group bookings down below.

We don’t have tours at specific time schedules, these are marked as visitors arrive. As you purchase your tickets our staff at the ticket office will tell you when the next tour will begin.

The tour takes about 60 minutes, starts with a small presentation video and is followed by an accompanied tour, our staff that will act as guide giving explanations during the length of the tour, and ends in a photography exhibition about the 70 years of cave exploration in Portugal and in a rock, mineral and gems exposition.

Because the staff aren’t certified guides, explanations in other languages depend on the staff’s own knowledge. Non the less, we have available a free downloadable APP that serves as an audio-guide with all the information for the cave in English, Spanish, French and German. The APP will work off-line during the tour.

During the length of the tour, we will walk 600 meters of cave and descend 683 steps, the largest staircase of the cave has 105 steps, comfortable shoes are advised.

The exit is by lift, about 300 meters from the caves entrance.

Groups and School Groups

Groups with 20 adults or more have discounts on the tour. These groups as well as school groups must be booked in advance and confirmed with at least 1 week remaining to the tour date.

The booking of groups must be made in writing to geral@grutasmiradaire.com providing the date, hour of arrival, number of visitors and a mobile contact number. For the school groups, the grade of the students is also required.

Groups with more than 45 persons must be divided into smaller groups that enter within 15 minutes apart as long as we have one of our staff members available to begin the tour.

Booked groups without confirmation might be overlooked by others with full confirmation.

In case of delay, the booked groups that arrive on time will have priority.

Group bookings are design to help manage our staff, they don't guarantee priority treatment.

Tariff 2024 (prices per person)

Free – Children under 5 years old
4,90€ - Children from 5 to 11 years old
8,20€ - All visitors with 12 years old and above
7,40€ - Group with at least 20 adults (if tickets are purchased by the leader of the group)

Taxes included at 23%

School prices (September to June)

1,60€ - Kindergarten
3,20€ - 1st grade (6 to 10)
4,00€ - 2nd grade (11 to 12)
4,70€ - 3rd grade, high school and college

Taxes included at 23%

Visit 5 Senses

The underground adventure begins here, on a visit where you will utilize your 5 senses. Experience the tourist cave and venture off the path to visit a parallel gallery like a true spelunker.

Total visit time approximately 120 minutes, who's up for the adventure?

No prior experience is necessary; the route we'll take isn't physically demanding, and there won't be a need for ropes or harnesses.

We provide helmets with built-in lights, gloves, and disposable suits. In the non-tourist section of the cave, the helmet light will be the only source of illumination.

We offer a small bottle of purified cave water for you to taste.

Please wear comfortable clothing that you don't mind getting dirty in case of any tears in the disposable suit. Wearing wellington boots is recommended, but you can also wear ankle-supporting footwear for the non-tourist areas. Bring a change of clothes and spare footwear just in case.

Reservations for this visit are mandatory with at least 4 days in advance, with a minimum group size of 2 and a maximum of 8 people. The minimum age for participation is 12 years old.

The visit costs €25.00 per person, payable at the time of booking and is non-refundable. However, it is possible to reschedule the activity.

Safety

Throughout the cave there is a security railing, it is there to protect both the visitor and the cave. Do not cross the railings for there is a risk of lesion. Avoid touching the cave walls and specially its formations as in doing so might prevent their future development.

Food and beverage

During the length of the tour the only beverage accepted is water, the only natural drink of nature. It is forbidden to eat inside the cave, chewing gum included, the only exception will be during events on proper locations.

WC

The tour takes about 60 minutes and there are no restrooms inside the cave. We have restrooms both at the beginning and at the end of the tour, including restrooms adapted to people with disabilities and changing room for infants. We advise the use of the restrooms before entering the cave, please don’t use the cave as a toilet.

TOBACCO

It’s strictly forbidden to smoke inside the cave, including vaping and electronic cigarettes, cigars and pipes.

Temperature inside the Cave

The cave as a stable temperature of 18ºC (64,4ºF), and high humidity.

You can bring a coat during the colder months for the return to the entrance (300 meters uncovered).

If it’s rainy outside, it will drip more inside the cave. You can take an umbrella for the return to the entrance, but please don’t open it inside the cave.

Photos and Video

It’s allowed to take photos and record videos during the tour so long as you don’t harm the natural flow of the tour. Remember to tag us @grutasmiradeaire

 
Pets

Pets are allowed inside the cave, so long as the remaining members of the group don’t mind their presence.

Strollers

Due to the nature of the cave, it’s impossible to use strollers during the tours.

Gallery of
Images