If you take a drive just 20-ish miles west on Highway 71 out of Austin, you’ll reach one of the most picturesque spots in the entire state: Hamilton Pool Preserve. The swimming hole has been a popular spot for Austin residents and tourists alike since the ’60s, but was actually formed thousands of years ago when the dome of an underground river collapsed.

Now part of the Balcones Canyonlands Preserve, the preserve is home to many rare and endangered species of plant and animals, including the golden-cheeked warbler bird and plants like canyon mock-orange and the chatter-box orchid. Visitors to the park are asked to be mindful of the efforts to preserve this natural wonder.

The natural pool and creek are natural, left untreated and pure for your swimming pleasure. The swimming area is surrounded by a tiny beach at one end and a massive, horseshoe-shaped limestone cliff around the rest. There’s even a waterfall opposite the beach, a much Instagrammed locale at the preserve. Because everything is natural, swimming at Hamilton Pool is sometimes off-limits due to high levels of bacteria. Updates are available every morning at 9 a.m. by calling 512-264-2740.

Unfortunately, as is customary, the “secret” of Hamilton Pool was unearthed in recent years, correlating with both the large growth in population and the influx of tourism as a result of the innumerable festivals and conferences inside city limits. Wait times to even enter the park reached into multiple-hours on weekends and particularly nice days, with a large majority of late-arrivers being turned away because the preserve had hit capacity.

To combat this, a couple of years ago the Travis County Parks Department implemented a reservation system for the busy season. A reservation is required if you want to visit the pool between now and October 31, 2018—and that goes for each and every day of the week.

To make your reservation, click here. But before you do, please note the following super important fine print:

“You make your reservation online by paying $11 with a credit card. You will also pay $15 per vehicle in cash for an entrance permit when you arrive at the preserve.  Credit cards are not accepted when you arrive at the preserve. Bring cash.

You can bring only one vehicle with each reservation. You can bring no more than 8 people with each reservation.

Your reservation receipt will be emailed to you very shortly after you make the reservation.

Reservation Periods: 9 a.m. – 1 p.m., 2 p.m. – 6 p.m.

No entry after 12:30 p.m. and 5:30 p.m. All recreational activities end at 12:30 pm and 5:30 p.m.

All fees are non-refundable once you have paid them. The deadline to reschedule a reservation is midnight before your reservation. You cannot reschedule on the same date as your reservation.

Swimming is sometimes not allowed due to high bacteria. Swimming is NOT guaranteed with your reservation.”

Got all that? It may sound like a hassle, but we promise it’s all worth it! Get yourself a rezzy and make the most of this amazing spot.