Coming in as a close second, the vast and unique landscape of the Gobi Desert captures the imagination of travellers, with a high percentage of reviews describing the Gobi Desert as unforgettable (10%). It covers the southern part of Mongolia and the northern and northwestern parts of China and is known for its dunes, mountains, and rare animals such as snow leopards and Bactrian camels.

The Amazon Rainforest, often referred to as the "Lungs of the Earth," is an unparalleled natural wonder that has captured the hearts and minds of countless explorers and eco-enthusiasts.

Whichever country Amazon visitors are seeing it in  (it stretches across nine! Brazil, Bolivia, Colombia, Ecuador, Guyana, Peru, Suriname, Venezuela, and French Guiana), they are blown away its sheer scale and incredible biodiversity, with 8.7% of the Amazon’s reviews describing it as an unforgettable or memorable experience.  From jaguars to sloths, spider monkeys to pink dolphins, the Amazon is home to millions of species of plants, insects and animals including mammals, birds, reptiles, and amphibians - many of which can’t be found anywhere else on earth. As well as its mind-blowing wildlife, the Amazon is also home to numerous indigenous communities that have inhabited the region for thousands of years. These communities have a deep cultural connection to the land and its biodiversity, and help preserve the Amazon as one of the world’s most memorable locations.

The Maasai Mara National Reserve has rightfully earned its place among the most unforgettable natural landmarks, as one of Africa's most celebrated destinations. It offers a front-row seat to one of nature's most spectacular events, which is the annual Great Migration, where millions of wildebeest, zebra and gazelle migrate in a clockwise direction across the ecosystems of the Serengeti (Tanzania) and the Maasai Mara (Kenya). It usually takes place at the start of July, but the timing depends on the rains.

Beyond the migration, the Maasai Mara is a year-round draw for wildlife enthusiasts. The expansive grasslands are home to the "Big Five" – lions, elephants, buffalos, leopards, and rhinoceros - ensuring a memorable experience. 

Following closely, in second place, is the "Giant's Causeway" in Northern Ireland, which attracts plenty of visitors who wish to witness the area’s unique hexagonal basalt columns, created by ancient volcanic activity.

Loch Ness, another Scottish gem, secures the third spot. Its mysterious allure and the legend of the mythical Loch Ness Monster draw in hundreds of thousands of visitors each year; even if there are no sightings of Nessie, visitors are still spellbound by the sheer size of the loch, as well as the tranquil and peaceful atmosphere it provides. 

Moving to England, the "Seven Sisters" cliffs follow in fourth place, showcasing the breathtaking beauty of the UK’s southern coastline. 

Scotland’s "Fairy Pools" (another entry from the Isle of Skye) captivate visitors with their magical and pretty charm, rounding off the top five of the most unforgettable natural landmarks in the UK.