The hashtag search function can find what you are looking for quickest. It would be a great place to start.
If you are looking for beautiful images, there are plenty of Tumblrs to follow. Just use the search feature, follow a blog or two, and then click on recommendations on the sidebar to amass a stream of European cathedral images or forest and wildlife images. I've been grabbing WW1 images from there to share with you all. Tumblr is far superior to Twitter in this regard.
If you want to check out smut, I'm not going to make recommendations but it is on there. After the purchase by Yahoo!, they blocked uploads of videos, but it looks like the wiz kids have found a way around that.
"I can do that anywhere, so why use Tumblr, 28Sherman?"
If you really want to have fun, use that hashtag to find some psychopaths to follow. It's "Human Zoo Internet". There are plenty of nutjobs. These people get boring after a while, so you need new replacements for a steady rotation. It is like a psychology class on "Modern Western narcissism crossed with Millenial faux sincerity, self esteem issues and SJW vibes". These people use a bunch of other's artwork, photography or quotes to create their digital representation. It is fun because these people are all timestamped 2015.
For several months now, I've followed an incredibly entertaining young British woman here. She's a strong woman of color (WoC) with massive mental issues. Her first Tumblr name was she's got issues. I'm not making it up. She changed it for some reason. By following her, I discovered Indians and whatnot are "taking back the Bindi" because white girls be wearing it for decoration. She posts some "white people steal shit" posts but then defending white people stuff. The most fun besides trolling was when a half black-half white girl called her out for being an attention whore who is dumb enough to post nudes for free. There are social issues to read for yucks from her. Guys, WoC want you to ask them about their background to show interest because we all know how much WoC ask white guys about their heritage (eye roll, dismissive wanking motion). I learned that WoC are strong women until they tell you every fourth post about the time they cried when they did not feel pretty for being a WoC. Besides her nudes and selfies, her photo posts are pretty standard issue for a part Indian-part white woman: many handsome white men, NSFW sex stuff to be edgy, food and rural European scenery with a smattering of ethnic stuff to keep it real. Her posts are now a regular rotation of crap, and I will stop following her shortly (after some trolling). It's not like I can't find nude photos of young WoC anywhere else. I would not post a nude of hers, but I'll post a pic she shared so you all can see this strong WoC, but I've tipped my hand already so you know what is coming.
Strong Woman of Color! "My hair gets frizzy when it is humid! I am not alabaster white! My eyebrows are bushy! Only 90% of the white guys I meet want me! I'm oppressed and carry a burden of being overlooked by white society even though I am part white!" This is why Tumblr is beyond parody.