SPOILER ALERT
The themes I'm going to cover are sadness, adventure, and acceptance. I think these themes are the most important I can relate to two of them.
Sadness is a big theme in this book because Turtle and her mom are no longer together. The reason they are not together is because her mom had to get a better job. They try to communicate, but Turtle's mom's boss is mean. On page 93 Turtle's mom writes her first letter to Turtle. It's also The Great Depression so people are affected by lack off work, inability to buy food, and many other aspects of the bad economy.
Two main adventures are being stranded on an island and a babysitting business. One of the adventures is starting your one bussiness because you don't know if it is going to be successful. Another exmaple is the treassure hunt to the island. They took a chance of getting lost and ended up becoming stranded when a storm came.
An example of acceptance is when they let Turtle in the Diaper Gang. She is the only girl and they had to sacrafice the no girls rule. Beans and Pork Chop are her cousins, so they persuaded the others to let her become part of the gang. Another example of of acceptance is when Turtle had to leave her mom. She understands she had to leave in order to make more money. She also understands that you can't always talk to someone.