Which animal of the world has the longest known hibernation period?

The longest-known hibernation belongs to a Cicada that hibernates for 17 years between emergencies. During the few months that the cicadas are active, they are incredibly loud and can exceed 100 decibels in volume!

https://www.dailymail.co.uk/sciencetech/article-9169949/Trillions-noisy-cicadas-set-emerge-spring-hiding-hibernating-17-years.html

Other animals that hibernate for a very long time include the free-living wood frog which hibernates for up to 7 months. There are also snails that can seal off their shells and hibernate for up to 3 years until conditions are more favorable.

https://a-z-animals.com/blog/discover-the-animals-that-hibernate-the-longest/#:~:text=Snails%20hibernate%20inside%20their%20shells,like%20a%20very%20long%20time.

https://gizmodo.com/which-animal-hibernates-the-longest-1571830549