Tumblr debuted its revamped Explore tab for U.S. mobile users Thursday.
The new Explore tab is available via iOS and Android, and Tumblr described its new features in an email to SocialTimes, adding that expansion outside of the U.S. was in the works:

Recommended Tumblrs: Personalized based on who you are currently following and the type of content that you and the people you follow engage with regularly.
Trending Topics: Top 10 topics that all of Tumblr is into right now, including the most popular tags and related content. Click to dive into any topic and seamlessly transition to the next top Trending Topic in a continuous scroll. Trending topics at this moment include: American Horror Story, NYFW, Blindspot, Undertale, South Park, Mr. Robot, GBBO, Champions League, BB18 and Moana. Ability to ?Follow? Trending Topics: Top content for that topic will become part of your regular content stream.

Tumblr users: What are your initial thoughts on the new mobile Explore tab"

...