Visitor attractions welcomed a quarter more visitors in 2021, but the numbers are still below pre-pandemic levels.
The Association of Leading Visitor Attractions (Alva) said there was strong demand for gardens, parks, forests and zoos in the UK.
But while visitor numbers were up 25% on 2020, overall they remain 57% lower than 2019, before the Covid outbreak.
However, those figures are not like-for-like, because attractions were not open for several months last year.
For the first time, the most visited attraction was not in London. Windsor Great Park saw 5.4 million visitors, while the second most visited attraction was Royal Botanic Gardens, Kew, which saw a 61% increase to 1.9 million.
Other popular attractions included Chester Zoo, the Natural History Museum, the British Museum, Tate Modern, Somerset House, the Science Museum, RHS Garden Wisley, and Forestry England's Jeskyns Community Woodland in Kent.
The average number of days that sites were closed in 2021 when they normally would have been open was 99, equivalent to 31% of regular opening days.
All visitor attractions were closed in the early months of 2021 during lockdown, but most restrictions were lifted by the summer. Even after that, some indoor attractions continued to open at reduced capacity and with reduced opening hours.
Alva said the total number of visits in 2021 was 67.8 million, but that's less than half of the 156.6 million visits in 2019 - when attractions were open for the full calendar year.
Overseas visitors restricted
Sites which are primarily outdoors had a less steep drop than their indoor counterparts. That is likely a result of restrictions on outdoor socialising lifting earlier in the year.
Gardens are almost back to pre-pandemic levels, Alva said, while Zoos remained 20% down.
But there was a much more significant drop for mixed sites such as heritage and cathedrals, which declined 51%, and primarily indoor venues such as museums and galleries, which were down 73% on pre-pandemic levels.
On average, sites that provided an international figure reported that just 4% of visits in the past year were made by visitors from overseas - a result of tight travel restrictions.
Bernard Donoghue, director of Alva, commented: "These figures, in a unique year, show that tourism was hit first and hit hardest by the consequences of Covid.
"There is a huge spectrum of those attractions, mostly outdoors, which are recovering well, but still many, mostly those which are usually heavily dependent on overseas visitors, are still just surviving."
He added: "Overseas visitors to the UK are not likely to be back to pre-pandemic levels until 2024/2025, so for many of our most iconic attractions this means not getting back to financial resilience for four or five years after having first closed their doors."
To improve overseas visitor numbers, Donoghue suggested the government could reverse its decision that EU school and youth groups need passports rather than ID cards to travel to the UK - a measure which came into effect in October.
The top 10 UK visitor attractions 2021
1. Windsor Great Park - 5.4 million
2. Royal Botanic Gardens, Kew - 1.9 million
3. Chester Zoo - 1.6 million
4. Natural History Museum - 1.5 million
5. RHS Garden Wisley - 1.4 million
6. British Museum - 1.3 million
7. Tate Modern - 1.1 million
8. Somerset House - 984,000
9. Science Museum - 955,000
10. Jeskyns Community Woodland - 878,000