It seemed like everyone we met this year was banging on about Game of Thrones or Stranger Things, so the most-watched TV show in Britain in 2017 came as a bit of a surprise.
It wasn't a sci fi or fantasy series or even a reality show like Love Island - Blue Planet II took the top spot with a viewership of 17 million.
The nature documentary series, narrated by David Attenborough, has won heaps of praise for its amazing storytelling and innovative use of technology.
It drew an audience of 10.6 million at its peak - for comparison, that's about half a million more than Strictly Come Dancing.
The show continues on Sunday night at 8pm on BBC One.