Apps with Music by Theme/Topic?

I am presently looking for an accessible music/radio app that arranges pieces/songs by topic/theme. For example, I might want to look up songs about "space" or "aviation" or "the sea" or "sailing". I am looking also for an app that might also suggest new music to me on these and other topics/themes. It would also be preferable if you could also select by genre and/or by artist. Does anyone know of any apps that would fit this description?

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songsza

it does not do quite what you want but it does have playlist bassed around moods and activities. I do not believe an app such as the one you are looking for currently exists. It would be pretty difficult to do since a program might not be able to figure out what a song is about very well. Besides lots of humans can't agree about what most good songs are about.

Songza again

Songza is also the first thing that cameto mind for me. I really love songza because not only are there playlists based on genres, but there are also playlists based on moods, decades, and a few other categories. If you can't find a playlist by browsing, there are tons you can find by searching because users can create their own public playlists. So you just might be able to find what you want because another user might have created just that. Always search for anything you can think of. There are many, many things I've found through searching that I would have never found otherwise.