Majlis Al Jinn (Meeting Places of the Genies) is one of my favourite caves in all of Oman. It is actually the world's second largest cave some say. Located in Al Sharqiyah Region of Oman, near the village of Finns in Wilayat Qurayat, tour groups can help you get there. If you are willing to pay more (and see more) you can take a helicopter ride to the entrance. The only way into Majlis Al Jinn is by rope and is recommended for expert and experienced climbers but if you are a novice you can hire a guide who will take you as you need specialised climbing equipment and someone has to know how to use it! :D
The cave gets its name because locals used to see the light reflected into the cave cast moving shadows on the cave walls, hence people thought Jinn (Genies) were inside it. What is really inside is a huge subterreanean lake, and very beautiful (colourful-rare) stalagmite and stalagtite rock formations.