Take the boat to Vermillion :P
Do everything in Island 1 2 and 3,then go back to Island 1 and go to Bill and Ceilio,after the conversation,Bill will lead you back to Kanto.
by taking the ferry but the ferry only takes you to the other isles how do i get back to kanto
You can't go back until you go to three island and find a lost girl in the berry forest once you do this talk to the girls father he is in the two island game corner and you will give him the meteorite now you go to the one island Pokemon center and bill will escort you to kanto.
If it is the first time you have been to the islands you must find the one guys daughter (which is on island 3 in berry forest by defeating a lvl 30 hypno) then to get off you must go to the dock (place where boat is) on any island and travvel back to vermilian city (thunder badge)
One of the Kanto gym leaders is in the island. Hopefully this helps! :)
Go to vermilion city and go to the dock where you entered the st. anne.
Blackthorn city, in kanto you find him at cinnibar island show him your 7 kanto badges to make him go back to the gym then you can battle him.
You need to have defeat the other gym leaders of Kanto first, after that you will find Blue on Cinnabar Island, talk to him and he will return to his gym.
Kanto is the map where you first start off not the island 1,2,3,4...
In the wild, it can only be found on one island.
Go to island 3 and enter berry forest and find a lost girl, save her from the hypno then when you get back to her dad give him the meteorite bill told you to give to him now go to one island and talk to bill he will take you back to kanto now you can finish the gyms.
Go to Cinnabar island and talk to Blue. He'll agree to go back to his gym and battle you.