Gruta do Lago Azul and Rio da Prata Snorkelling

While travelling through South America (La Paz to Rio de Janeiro) with G Adventures we met up with fellow travellers that had travelled from Brazil in the Salt Flats in Bolivia. We were chatting about best things to do in Brazil and they told us about Rio da Prata which was apparently not to be missed (they had missed out due to not knowing to pre-book). While I had wifi I contacted the hotel we were staying in Bonito and tried to get all of us on the tour as we didn’t want to miss out. We had almost 2 weeks to wait and see what was to come, but we were assured it was spectacular. Its the only activity in my years of travelling that I have booked that far in advance.

When we got to Bonito we were greeted by thunderstorms – all afternoon and night. It was very impressive. We had arranged to also go to Gruta do Lago Azul (Blue Lake Cave) in the morning then head off to snorkel in the afternoon however due to the storms and the amount of rain coming down both activities might be cancelled and it would be the only day we could do both as we were leaving the day after. We tried to get sleep through the storms and hope that the trip we had planned weeks ago would not be cancelled.

We got up at 6:50am for 7am departure to head out towards Gruta do Lago Azul, not knowing if it would be open for us to venture down to see. The weather had finally cleared up and the sun was shining and the ground had already started to dry up so we were all hoping that the water might have subsided. Thankfully when we got there they had the open sign out.

Gruta do Lago Azul means Blue Lake Cave. As the name suggests its a cave with stunning blue waters. Amazingly we had to wear hard hats to go down into the cave (so far in Brazil the health and safety had been lacking). There are ALOT of steps going down into the cave, these were very slippy from the torrential rain the night before.

As you descend into the cave you are surrounded by stalactites and stalagmites. The tour guide did speak a bit of English but our G Adventures guide decided to come along for the entire day so she helped with the translation.


Between September and February the waters are an intense blue colour. There are prehistoric fossils which have been found in the cave which unfortunately you cant see, fossils include a giant sloth and a sabre-toothed tiger. You can spend hours staring into the beautiful blue water and trying to capture the perfect shot. The photos below have not been enhanced on photoshop – it really is that blue!


From The Gruta do Lago Azul we headed towards Rio del Plata. We had a lovely afternoon chilling out in the hammocks and enjoyed a very delicious buffet lunch. We waited around for around an hour and a half before we were called to get kitted out in wetsuits. The area is protected so wetsuits are mandatory to protect the waters, they also ask you not to have freshly applied suncream as well as it can pollute the water.

The tour starts with a 4×4 drive to the start of the trail which leads through the forest of the Prata River and its tributary Olho D’Água River. The area is protected by a Private Reserve (RPPN). The trail leads to the main spring of Olho d’Água River where the snorkeling tour begins.


As soon as you get in the water you are amazed about how crystal clear the waters are. We snorkelled around the entry area for a while, so you could adjust the snorkel mask and for the guide to make sure you would be safe and listen to his instructions. The tour was amazing, the waters were so clear, there were hundreds of fish all around you. I have uploaded some videos and photos from the tour, however it doesn’t capture the tranquillity of the area or just how beautiful and how well the Brazilians look after the Olho D’Água. They are very proud of the area and try hard to keep it pristine for future generations to enjoy.


The video below is further downstream so there are less fish but still the crystal clear waters and surroundings make it very enjoyable. You don’t really need to swim, just float and let the light current take you downstream. They do ask you not to move arms and legs much in the water as well so you don’t disturb the ecosystem.

You do have to get out at one point along the way and walk for a bit, this is so you don’t get taken down some white water. You get straight back in though and continue your journey towards Prata River. There is a large area where you can jump in and take some good photos. None of us wanted to do this but we did take a couple of underwater shots.

From this point you continue downstream and you can tell immediately then you hit the Prata River as the water temperature drops a few degrees. You do have the option to get out here if you are tired or cold, or you can continue snorkelling downstream to the get out point. The river is not as clear here but there are some really big fish you can see which are worth it.

Overall this trip is well worth the money, it might not be cheap but the memories last a lifetime!


Author: Globetrotting Expeditions

I love the great outdoors and travelling, so I try and combine them as much as possible. I am also a massive fan of F1. My goal is to someday summit an 8000m mountain, but hopefully I will get to climb many other mountains along the way.

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