Four lucrative side hustles for summer, as shared by high-income earners.

With summer's arrival comes travel, concerts, amusement park trips, and a new wardrobe, which can add up to a lot of expenses. To avoid overspending, you might want to consider taking on a summer side hustle to earn some extra cash.

CNBC Make It interviewed numerous individuals who demonstrate that side hustles can generate more than just a few extra dollars; their side hustles typically bring in over $100,000 annually.

"For the past three and a half years, Sophie Riegel, a part-time online clothing reseller, has been doing her side hustle and wouldn't trade it for anything else. She loves it so much and it brings her immense joy."

This summer, you can explore four ways to earn money while having fun.

1. Resell clothing

You can continue spring cleaning and turn it into a sustainable year-long side hustle by selling unwanted things.

In 2020, as a bored Duke freshman during the pandemic, Riegel began selling old clothing items in her childhood bedroom. After making approximately $200 from selling some of her own unused items, she became addicted to the activity.

In 2023, she made $123,800 by buying cheap items from thrift stores and reselling them online on platforms such as eBay, Poshmark, and Mercari.

Riegel's primary occupation involves working as a professional writer, mental health coach, and speaker. She revealed to Make It that she dedicates approximately 25 hours per week to her side hustle.

Her success is largely due to her thorough research on various aspects, including item worth and restocking schedules at nearby stores.

"According to Riegel, although technically thrifting takes the most time, it doesn't feel like work to her."

2. Rent your pool

In 2012, Jim Battan invested $110,000 in constructing a pool at his West Linn, Oregon residence. Currently, the pool has not only recovered its initial cost but also generated additional revenue, as Battan stated in 2022.

Battan earned $177,000 in less than two years by renting his pool on the Swimply app.

Battan cautioned that not everything goes smoothly when it comes to pool management. To be successful, one must learn about pool chemistry and management and dedicate time to checking the pool's chemicals 5 to 10 times a day. Despite the effort, it can be a rewarding side hustle.

"Battan stated that he views his pool as an investment and takes it very seriously. However, he observes various hosts on Facebook posting about adding chlorine to their pools and asking if it is sufficient. Battan believes that this is only the beginning of the maintenance required for a pool."

3. Showcase your career through content creation

Kelly Gordon is a superyacht captain by day and earns $10,300 a month through her side hustle of creating social media content, which she spends about five hours a week on.

In 2007, Gordon discovered yachting after attending a wedding reception on a boat. Despite not knowing the difference between port and starboard, she asked the captain for more information about the profession the next day.

Now, Gordon provides viewers on Instagram with information about yachting. She generated $124,000 in revenue in 2023 through sponsorships, merchandise sales, ads, affiliate marketing, and public speaking engagements.

Despite her success in content creation, Gordon remains in her day job. Her side hustle thrives because she continues to yacht.

"I'm not done running boats anytime soon," Gordon said.

4. Rent out your car

During the summer travel season, individuals embarking on road trips across the United States frequently seek car rental options. Andrei Echeverria's side business provides an alternative to traditional car rental services. Through the Turo app, he rents out his six cars and has earned up to $14,000 per month, as reported by Make It in 2023.

Echeverria, who resides near Boston Logan International Airport, has an advantage over other Turo users in finding renters due to the app's ability to set prices. As a result, he can offer more attractive rates than the rent-a-car counters.

Echeverria stated that the success of his side hustle relies on establishing relationships with local repair shops and gaining their trust. He dedicates eight to 10 hours per week to managing, cleaning, and booking his cars.

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