There's never a bad time to visit a national park—it's an unforgettable experience, even during the winter. But from the end of May through the very beginning of June, you can see something incredible unfold at the Great Smoky Mountains National Park: a firefly mating ritual. For two weeks, thousands of Synchronous fireflies descend on a special area of the park near Elkmont to put on quite the synchronized light show.

Travelers have planned vacations around the event for years, but park officials have enforced a lottery system for obtaining passes to the light show in and effort to protect the bugs. In previous years, passes sold out in seconds online. This year, the park is doling out passes using an online lottery system. The lottery for all 1,800 parking passes will open up at 12pm on Friday, April 29th and will remain open to the public until 8pm on Monday, May 2nd. Anyone who received a pass to the park during the mating season will be notified via email on May 10th. While the lottery is free to enter, there will be a $1.50 reservation fee to pay for anyone who receives a ticket—a small price to pay for check on the bucket list.

No video could ever do the in-person experience justice, but check out the video above for a taste of what you can expect to see.

Erika Owen is the Audience Engagement Editor at Travel + Leisure. Follow her on Twitter and Instagram at @erikaraeowen.