Founded in 1828 the museum houses around 67,000 specimens many of which are now extinct or endangered. My favorite is the skull of a Bottlenose Whale from 1860.
I love swimming and I love being outside. London is great if your into both these things. I swim at London Fields Lido which is heated all year round. Its best in the winter when the steam rises from the water and if your lucky its snowing a little on your head. If your brave you can also go for the unheated option of the Serpentine or Hampstead Ponds.
I love how much you are aware of the changing seasons out of the city; there are numerous beautiful forests around Hertfordshire to go for a run, a walk or have a picnic. One of the best destinations for a day out from London might be Northaw Great Wood. The main entrance is located on the Ridgeway, the B157 from Cuffley to Brookman's Park.