Dr. Sylvia Earle explores the Great Barrier Reef in a scene from 'Mission Blue' (© Bryce Groark/AP Photo/Netflix)

Trillium Lake in Mount Hood National Forest, Oregon, USA (© Frank Krahmer/Getty Images)

Moai statues at Ahu Tongariki in Rapa Nui National Park, Easter Island, Chile (© blickwinkel/Alamy)

Sigiriya Rock, Central Province, Sri Lanka (© Jeremy Woodhouse/Getty Images)

Gefärbte Wolle auf dem Rossmarkt in Berching, Bayern, Deutschland (© Rüdiger Hess/geo-select FotoArt)

A snowdrop in bloom (© Péter Hegedűs/Getty Images)

View of the Old City in Quebec City, Canada (© RENAULT Philippe/age fotostock)

Lantern Festival in Pingxi, Taiwan (© Jung-Pang Wu/Getty Images)

The Hollywood sign overlooking Los Angeles, California (© Sean Pavone/Shutterstock)

Aerial view of Superkilen Park in Norrebro district in Copenhagen, Denmark (© Oliver Förstner/Alamy)

Pinzon Island tortoise hatchling emerging from its egg at the Charles Darwin Research Station on Santa Cruz Island, Galápagos Islands, Ecuador (© Pete Oxford/Minden Pictures)

Lahori Gate of the Red Fort, Delhi (© powerofforever/iStock/Getty Images Plus)

A heart-shaped hole in the rock formation of Calanques de Piana in Corsica, France (© joningall/Getty Images)

Humpback whale feeding on herring off the coast of Kvaløya, Troms, Northern Norway (© Espen Bergersen/Minden Pictures)

The 2019 Lemon Festival in Menton, France (© Mandoga Media/Alamy)

Frozen colosseum of ice sticking to the columnar basalt walls surrounding Abiqua Falls, Oregon, USA (© Joshua Meador/Tandem Stills + Motion)

Pluto's crescent imaged by NASA's New Horizons interplanetary space probe (© NASA/JHUAPL/SWRI/Science Photo Library)

Statue of Shivaji in Solapur, Maharashtra (© Dinodia Photo/Getty Images)

Rifugio Lagazuoi above the clouds with Monte Pelmo in the background, Dolomites, Italy (© Nicolo Miana/eStock Photo)

Elephanta Island caves near Mumbai, Maharashtra (© Andrey Khrobostov/Alamy Stock Photo)

The interior of the Great Temple of Ramesses II, Abu Simbel, Egypt (© Nick Brundle Photography/Getty Images)

People ice fishing on Gull Lake in Brainerd, Minnesota, USA (© Robert Benson/Cavan)

Pilgrims throwing wind horses into the air above Ganden Monastery for the New Year in Tibet, China (© Ian Cumming/plainpicture)

The Roots of Music Cultural Sculpture Garden in Louis Armstrong Park, New Orleans, USA (© jejim120/Alamy)

Acadia National Park in Maine, USA (© emptyclouds/Getty Images)

A polar bear sow and her cubs in Alaska's Arctic National Wildlife Refuge (© Steven Kazlowski/Minden Pictures)

Otter Creek in winter in Brandon, Vermont, USA (© Caleb Kenna/Offset)

A Wallace's flying frog glides to the forest floor (© Stephen Dalton/Minden Pictures)

Scenic deep tropical forest of Janjehli, Himalayas (© KS-Art/iStock/Getty Images Plus)