A rolling cloud sweeps over the top of Bar Island as seen from the summit of Cadillac Mountain.

The best show on Mount Desert Island: dawn.

People unload their vehicles in the blue, pre-dawn light on the top of Cadillac Mountain as a steady stream of traffic heads toward Mount Desert Island along Route 3 at 3:40 a.m.

Raven's Nest, a secluded spot on the Schoodic Peninsula side of Acadia National Park, seen on a gray day.

Dawn in purple, red, orange and blue from the top of Cadillac Mountain.

Bicyclists on the Park Loop Road ride past a long row of parked vehicles near Sand Beach.

Pre-dawn on top of Cadillac Mountain where hundreds wait daily for the first glimpse of the sun in the United States.

Hundreds of people gather at the summit of Cadillac Mountain in Acadia National Park to watch sunrise.

A 30-second exposure blurs the crashing surf along a stretch of rocky coast on the Schoodic Peninsula.

Visitors (including one with very sandy legs) on the stairway to Sand Beach.

The Porcupine Islands from the top of Cadillac Mountain as pre-dawn colors fill the eastern sky.

Hundreds of people gather at the summit of Cadillac Mountain in Acadia National Park to watch sunrise.

A 30-second exposure blurs the crashing waves at Raven's Nest, a point along the Schoodic Peninsula inside Acadia National Park.

ACADIA NATIONAL PARK, ME - JUNE 27: Three people walk down from the summit of Cadillac Mountain after watching sunrise Monday, June 27, 2016. (Photo by Gabe Souza/Staff Photographer)

Tourists flock to Thunder Hole, trying to get a glimpse of the famous waves that make a crashing sound against the rocks.

Hundreds of people gather at the summit of Cadillac Mountain in Acadia National Park to watch sunrise. Between March and October, the sun is seen first here and then touches the rest of the coast.

The rising sun peeks over the summit of Cadillac Mountain as hundreds of visitors leave after witnessing the first view of the sun in the United States.