There aren't many tourists, but I'm sure there are a lot of locals.
ご質問ありがとうございます。
「観光客」はtouristとsightseerと言います。そして、「近くの住民」はlocal resident（短縮：local）です。「少ない」と「多い」で人数の話になりますので、touristとlocalを複数形にしないといけません。
他の言い方：There aren't a lot of tourists, but there are probably a lot of locals.
ご参考いただければ幸いです。
You don't see a lot of tourists there, but quite a few locals go there.
There aren't a lot of people from out of town at that restaurant, but you see lots of locals there.
この場合、次のような言い方ができますよ。
ーYou don't see a lot of tourists there, but quite a few locals go there.
「そこで多くの観光客は見ないけど、地元の人は結構行く」
ーThere aren't a lot of people from out of town at that restaurant, but you see lots of locals there.
「そのレストランには住民以外の人は多くないけど、地元の人はたくさん見かける」
ご参考まで！
アメリカ合衆国 
カナダ 
