Smithsonian Networks is entering the booming subscription streaming space, announcing the launch of Smithsonian Channel Plus.

The ad-free, on-demand platform will cost $5 a month for access to more than a thousand hours of programming spanning history, air and space, nature and wildlife, science, travel and pop culture.

Smithsonian Channel Plus adds to the overall offerings affiliated with CBS Corp., which has rolled out CBS All Access and Showtime in the SVOD space and an array of ad-supported services around sports, news and entertainment. Smithsonian Networks is a joint venture of CBS-owned Showtime and the Smithsonian Institution.

Competition has intensified for viewers’ streaming dollars, with more than 230 SVOD services now operating in the U.S., according to a recent tally by Parks Associates. With downward pressure continuing on all networks’ linear ratings, most programmers have turned to streaming to replace lost affiliate and ad revenue.

Smithsonian’s app will refresh its content weekly and feature past full seasons of series like Aerial America, America in Color, Million Dollar American Princesses, The Lost Tapes and Air Disasters. Also included will be Smithsonian Earth’s nature and wildlife titles in 4K UHD.

“We are thrilled to be able to bring Smithsonian Channel’s acclaimed programming to new audiences in an easily accessible way at a time when viewing habits and consumption are rapidly changing,” said Tom Hayden, President, Smithsonian Networks. “With a deep and varied programming library, including one of the largest offerings of 4K UHD content, launching Smithsonian Channel Plus allows us to super-serve viewers who love documentaries and series across a wide variety of genres.”

Smithsonian Channel Plus will be available through the Smithsonian Channel app on Apple, Amazon, Roku and Android devices or through the channel’s website. By the end of 2018, Amazon Prime members will be able to subscribe to Smithsonian Channel Plus through Prime Video Channels.