places near Bangalore that are hard to believe exist until you visit them

There are many such places in Karnataka.
1. Kavaledurga is a magnificent fort located on a hill at an attitude of 1541 mtrs. The Kavaledurga fort, sometimes called the Bhuvanagiri fort, is situated in Shimoga district. Among the many forts of Karnataka, one that cannot be missed is Kavaledurga. There are interesting stories and fables tagging this fort many temples of various deities. According to Hindu legends, this place is called as Parashuram Kshetra and was famous in Krita Yuga. In Treta yuga sage Agastya and Valmiki had stayed here. In Dvapara Yuga there are legends which tells that the Pandavas had stayed at this place for a while. Bhuvanagiri durga is also mentioned in the Skanda Purana by the name Kavya vana and Kapila durga. 

The fort is the ideal picnic spot for trekking enthusiasts.
2. Merthi Betta: Merthi Peak is a part of the Chikmagalur Range (along the Western Ghats) near Sringeri. It is 340 kms from Bangaluru. The 360 degree unhindered view at the peak with the breeze hitting you hard takes over the little tiredness that you had.

3. Suparshwa cave (Guppipari guhe): Kamalashile is home to the Brahmi Durgaparameshwari temple. Speciality about Kamalashile is the fact that goddess Brahmi Durgaparameshwari is worshipped in the form of a 'Linga' here. Also special is Suparshwa cave, which a local legend says, is visited by a tiger. Kamalashile is a small temple town in Udupi district's Kundapur taluk, Guppipari guhe is about a kilometre from this temple. Its the birthplace of 'Naga Teertha', which, mythology has it, later became River Kubja. A mythological episode has it that long back, fearing death from Garuda, Adishesha came to goddess Brahmi Durga Parameshwari seeking liberation from a curse. The goddess advised him to seek Lord Vishnu's help and requested all the other nagas (serpents) to hide in Suparshwa cave, so she could save them from Garuda.

4.Tilmati : Beautiful Black Sand Beach in Karnataka
This beach is very clean & unpolluted. Here no crowd; no plastic's, very hygienic & also we can reach very easily, only 15 minutes trekking itself. After crossing one small stream we climbed two three small mountains & we saw this spectacular black sand beach.
Generally, the sand becomes black when it originates from a volcanic irruption. This small beach is set among lava cliffs and the sand is actually small, smooth, lava pebbles.

5. ParpiKallu -The terrific rock formations: 'Parpikallu' in near Dharmastala. ( near Kokkada on Subrahmanya-Dharmasthala route)
It is an idyllic spot guaranteed to take your mind off the jarring fall of city life. The river 'Kapila' tumbles over huge rocks crating the falls. The highlights the gushing water at angles that brings out the magnificence of this thunderous beauty.
This is famous for its variety of natural rock designs.

6. Narasimaha Ghad fort: the fort is located near Beltangady town. It is 1788 ft above sea level & it is also referred to locally as 'Jamalagadda'. The fort was built by Tippu Sultan in 1794 and named after his mother, Jamalbee.

The nearly 1876 steps to the fort are cut out of this granite hill and lead all the way to the top through the fort to the summit.
The fort was captured by the British in 1799 during the 4th Mysore war. Legend has it that those out of favor with Tippu were hurled down this fort to their death.

7. Betebare Mountain (HaddinBare) and Siddargundi Waterfalls:
Siddaragundi falls is situated in the Mookambika range. A beautiful water fall, it was like a scene taken right from the fairy tales where one could imagine all angels bathing in that clear pool of water with water flowing in a magical way on the rocks anyone gets engrossed in it's beauty. 

There is another water fall short distance from where we were where many small water falls join to make a splendid falls called Tirthabare falls.

8. Ulavi Caves: Ulvi (Ullavi) Caves are a bunch of caves in the Uttara Karnataka District of Karnataka. They offer a continuous circuit of trekking trails that allows you to explore gloriously dark rock caverns.

PS: These being Malnad area in many of these places there are snakes, in which some species are even poisonous, so if you plan to trek in these area beware of that.