Housing development around the region began in the late 20th century with non-governmental organisations expressing concerns about the over-development.

[12][13] The Batu cave system and its caverns is a biodiversity hotspot consisting of many plant and animal species, many of which are specific to such limestone environments.

[15] There are a diverse range of cave fauna, including endemic species such as the trapdoor spider Liphistius batuensis.

The dark cave system is home to numerous species of insects including haplotaxids, spiders, mites, ticks, scorpions, springtails, beetles, flies, ants, wasps, bees, butterflies, moths and other animals such as frogs, lizards, snakes and snails.

Development over the years, industrial activity, and the high number of footfalls due to the religious site are threats to the biodiversity in the region.

[14] The similarity of the entrance to the cave structure to a vel (a spear) wielded by the deity Murugan is said to have inspired Thamboosamy to build a temple.

In the 1930s, the stairs began to show signs of wear and a decision was made to build concrete steps on the southern side of the cave complex.

[1] To the right of the steps which serve as an entrance to the cave complex, a 42.7 m (140 ft) tall statue of Murugan was unveiled in January 2006.

Kavadi Aattam is a ceremonial act of sacrifice and offering practiced by devotees, which forms a central part of the festival.

The most extreme and spectacular practice is the carrying of Vel kavadi, a portable altar decorated with peacock feathers and flowers, that is attached to the body of the devotee through multiple skewers and metal hooks pierced into the skin on the chest and back.

[29] Devotees usually prepare for the rituals by keeping clean, doing regular prayers, following a vegetarian diet and fasting while remaining celibate for 48 days.

A silver chariot weighing 350 kg (770 lb) carrying the idols of Murugan with his consorts Valli and Deivanai is taken along the procession, accompanied by the devotees.

These climbing routes can be accessed from the ground level with abseiling and spelunking trips organized by local companies.