This is an area in the new zone, The Lost Island. It was made in a recent update where there are many evolved critters to fight (sadly, you cannot catch)! You must help the cottonweed-like things (Swoopy) rebuild their city from the Puppet Master's goons (the evolved monsters on the island)
If you click on the zone through the map, you enter Central Town. There, you must go up to the "Island Center" Area, where you meet two Monster Guards. There, you have 4 doors to pass through.
The far left brings you to the "Western Shore", with two doors and two Monster Guards. Go through both doors and that will bring you to "Northwest Area".
The "Northwest Area" has two more doors and three Monster Guards.
The middle left brings you to "Swing Bridge", where you must defeat a Monster Guard at the middle bridge.
The middle right brings you to "Northeast Area", and you can get the secret member chest!
The far right brings you to the "River Bridge" with one door and three Monster Guards. Go through the door that will bring you to "Northeast Area", with two more doors and three Monster Guards. The both doors brings you to "Swing Bridge", with two more doors and a single Monster Guard.
Oh no! The Puppetmaster destroyed the Central Town and you must collect wood from 6 of any monster (each defeated monster gives you 2 wood). Come back to Swoopy and it'll say, "You completed today's quest. Thanks for getting some of our wood back! Don't forget to come back tomorrow!"