There's even more to explore in the world of Calico with the Neat Things DLC, including:

-New Quest — Neat Things Scavenger Hunt: Your beloved aunt has a mission for you that takes you across the whole island in search of some really neat things!
-New Area and NPC — Mermaid’s Cove: Visit Clover Cove to uncover a new area, and meet a mythical new friend — Nahla the Mermaid!
-New Animal Companions: Become best buds with new cuddly friends, including a mischievous raccoon, a smiley axolotl, a playful elephant, a loveable golden retriever, and, of course, a very familiar cat!
-Two New Mini-Games: The Cutie City arcade has two new activities to enjoy, so be sure to pay it a visit!
-New Café Decorations: Create your dream aquatic-themed cafe with furniture!
-And More to Discover: Have a wander around the island and explore the world around you to uncover some fun new interactions such as playing in piles of fallen leaves, making a wish on dandelions that have gone to seed, and more!

More details on the official game page of Calico: Neat Things ...