Puncak Jaya, also known as Carstensz Pyramid on the island of New Guinea, is the highest peak found in Oceania. It competes for the rank of the Seventh Summit with Australia's highest peak—Mount Kosciuszko. Puncak Jaya is over twice as high as the Australian one, namely 4,892 m. Besides the height itself, the steep rock is extremely challenging to climb in technical terms.
Equatorial climate makes the journey even more arduous, the weather is constantly changing at any time of the year—get ready to be frequently washed with bad rainstorms, then burnt with the sun, and on the final ridge, you're very likely to be heartily welcomed with a snowstorm. You'll need some really good equipment, and a few pairs of gloves, for they will surely tear apart.
While such chaos prevails in the highlands, the rainforests in the lower plateau may boast at least some climate order. Taking into account that you'll have to make your way through these rainforests to get to the mountain, it would be wiser to choose dry season—between April and November.
Technical complexity is not the only obstacle. Another problem is the red tape. Months and even years can pass by until you've undergone all procedures, and received all necessary permissions. If you don't apply to any local operator and choose to arrange everything on your own, you may finally get your license, but don't be surprised when it turns out to be invalid. Taking into account political issues and constant tribal wars, it's strongly recommended not to spare money, and go on an organised climbing tour. It will cost about 25,000 USD.
The first Europeans got to the summit in 1623. It was a Dutch expedition led by John Carstensz—hence comes one of the mountain's names. When the group of climbers returned back to Holland, it was difficult to convince people that travellers had seen snow-capped mountains close to the equator.