After you finish the island, the Chupacabra and Jersey Devil are long gone, and if you visit the Northwest, all you see is the caves. Likewise, if you take the rowboat Lil' Ness back to the lagoon, Nessie has swum away and doesn't answer the whistle.
One thing you can do is explore the main island, and fly a kite from the store. Like the balloons on Counterfeit Island, the kites let you jump higher. But you can't take them to the foreign locations.
Go into the kite store and talk to the lady, and she will let you borrow one for free (just click on any of the kites). You can return it when you are through, or it will appear again the next time you visit Cryptids Island. A kite is like a large "follower" anytime you are outdoors on the main part of Cryptids Island (not the other geographic locales). Like the balloons on Counterfeit Island, the kites lift you up, so you can jump higher. In fact, you can see the entire "Bigfoot or Bust" pedal-blimp at Cliff Park.
On your first visit to Loch Ness, you can win a rowboat ticket by playing darts at the Pub (to the right of the Loch).
The first thing you do, as you must eventually go to the right from the blimp, is to get a handbill explaining the quest for cryptids. The millionaire Harold Mewes is seeking evidence to prove their existence. Your first act can be to visit the store, or the kite shop, but you can do nothing until you have acquired the $5 bill, which is in a tree by the right on Mansion Row (right from Main Street).
On your second visit to Puerto Rico, the herder is setting a trap at the Snaggletooth Rock (center star on the jeep map). Herd the three spotted goats into the grass circle as bait, then join the herder at the rocks.
You can summon Nessie with the pennywhistle. You can lure the chupacabra (on your second visit to Puerto Rico) by herding 3 spotted goats into the area of Snaggletooth Rock (center star on the map). The farmer will prepare a trap there.
He leaves when you come back to Loch Ness and confront him. On your first visit, he takes you to get a photo that turns out to be just old tires. After you show it to Mews, go back to tell him off, and win a submarine ticket in the Pub.
The proof is at each of the locations, but there is some less-than-convincing evidence. You get a photo of Nessie at Loch Ness that is faked, and another one that is a movie prop. But you finally get a real photo. You find some fur on your first visit to Puerto Rico that turns out to be coyote fur, but you return to trap the chupacabra. You find a footprint in the snow in the Himalayas that is unconvincing, but when the three other cryptids are proven, you get to hunt for Bigfoot instead.
On your first visit to Loch Ness, you win a rowboat ticket at darts, but only get a photo of some old tires from the rowboat. On your second visit to Loch Ness, you get the submarine ticket from the other dart players, but your underwater photo of the bottom of the Loch is only a movie prop. Go back to the pub to beat the first dart player again (a poor sport) and the bartender will give you the pennywhistle.
All of the darts players are at the pub when you arrive. On your first visit, beat the man wearing glasses to get a rowboat ticket, and take your photo back to Mews. On your next visit to Loch Ness, you will play against the second player, who will give you the submarine ticket. Bring your underwater photo back to the pub and you will get to play the first player again, who proves to be a poor loser.
On your first visit to Loch Ness, you win a rowboat ticket at darts, but only get a photo of some old tires from the rowboat. On your second visit to Loch Ness, you get the submarine ticket from the other dart players, but your underwater photo of the bottom of the Loch is only a movie prop. Go back to the pub to beat the first dart player again (a poor sport) and the bartender will give you the pennywhistle.
You will come face-to-face with Nessie on your second trip to Loch Ness, after two earlier photos prove to be worthless. You will meet the Chupacabra on your second visit to Puerto Rico (the first trip yields only coyote fur). You see the Jersey Devil at an abandoned house in the New Jersey forest. You will fly over and fly with Bigfoot after the other three are proven. The Yeti version of the Bigfoot is never found. (see related question)
You use the helicopter to fly to the various locations on Cryptids Island.The GPS is initially set up for the Mews mansion and 4 other locations, and it is to your advantage to visit them in the order they are shown.(Mews Mansion)Loch Ness, Scotland (need a photo of Nessie)Himalayan Mountains (looking for proof of the Yeti)Puerto Rico (need a DNA sample of the Chupacabra)New Jersey (need a DNA sample for the Jersey Devil)(see related question)