By collecting cargo then trading cargo for money but be sure to get a good deal ( $23 at lest) Hint: Have war and win to get quick cargo then buy higher costing ships.
get salvage
it costs 1,000,000 ( one million ) doubloons. that's a lot of money! trade a lot, and EVERY day and it wont be long before you acquire it.
You keep trading to get enough money.
if your talking about on skullduggery island you have to save up your money to buy one. (poptropican money, and not in the store)
There are no cheat codes on Poptropica. (see the related question)
search this on youtube;GET MILLIONS OF DOUBLOONS IN POPTROPICANA ! REALREALREALThen watch.
you need a lot of dabaloons. You can get them by finding salavage and trading goods
you need to get money and buy a boat then you can go to the other islands
you go around to each place and sell your cargo
there is no easy way to make money you can trade and buy stuff cheap and trade and sell it high of just find money while your sailing.
Skullduggery sea is in the bottom left on the map
Usually Parrot Port, for between 32 and 40 doubloons.