Junior Researcher Nick Gates was able to smell an adder from a distance which led to the team being able to film the snakes in the wild.
Sir David Attenborough visited Skomer Island twice during filming, which involved him climbing 87 steps to access the island from the boat. He practiced by climbing his stairs at home.
The Wild Isles team spent 1,631 days in the field filming for the series.
The longest individual shoot for the series was for the Atlantic salmon sequence in the Freshwater episode, which took 71 non-consecutive days to film over two years.
Sir David Attenborough is 96 years old when this airs, making him one of the oldest TV presenters for his career.