Carnival is known for ultra-cheap cruises. I sailed on its new ship — and I'm not sure that's completely true.

Well, not quite.

You'll be met with a flurry of tempting up-charged amenities the moment you board Carnival's ships. So, if you're prone to giving into these little luxuries, you can kiss your budget goodbye.

I paid $735 for a solo interior cabin, including optional gratuities.

If that sounds relatively expensive, you'd be right. Carnival Firenze is the company's latest vessel, and newer cruise ships generally command a pricing premium.

It's also worth noting that I had booked it less than 10 days before embarkation. Oops.

Mass-market cruise lines have been increasingly slapping fees on on-board amenities and activities. I knew excesses like alcohol, WiFi, and specialty dining would cost extra, as is typical across the industry.

Cocktails were generally about $13, while beers and seltzers were about $9 each. Specialty restaurants like teppanyaki and Italian cost about $40 per person, while the steakhouse was $49.

None of these were surprising. Even premium cruise lines charge extra for higher-end restaurants and beverages.

Even complimentary dining venues dangled tempting dollar sign-afflicted dishes — including the buffet, where guests had to pay for chicken wings.

Craving a lobster roll? The dinnertime Seafood Shack booth (which otherwise has free breakfast and lunch options) sells one for $18.

Looking for some pizza? You could grab a free pepperoni slice at the pizza stand — or pay $6 for the fancier Korean barbecue steak pie.

I had been craving a juice for breakfast. Too bad it was $5 (in the complimentary main dining room, no less).

I would've loved some popcorn during the evening movie showings. A bag costs $4.

During our second stop in Ensenada, Mexico, I briefly considered taking the shuttle from the port to downtown. However, that would've been another $4.

The daily schedule denoted pay-to-play events with a small dollar sign symbol. "Tea Time" didn't have one, so off I scurried, excited for some free mid-afternoon caffeine and sweet treats.

You can probably guess where this story is headed.

After I took my seat, a waitperson arrived at my table with an organized box of tea bags, giving me just enough time to review my options before announcing they were $1.50 each. On principle, I declined.

A few minutes later, he returned to my table to let me know that he did, in fact, have some free options stashed behind the up-charged bags. They were the same as those available in the buffet: Lipton and Bigelow's green tea.

I knew he was kidding, but for a split second, I was worried he wasn't. At that point, I expected almost everything I wanted to come with a price tag.

But not being immediately upfront about the $1.50 tea bag and otherwise free options felt unecessarily deceitful.

In the company's defense, not everything had a price tag. Fun activities like the mini-golf course, waterslides, and fear-of-height-inducing ropes course were complimentary and great for forgetting how annoyed I was about "tea gate."

There's a reason onboard spending has skyrocketed over the last year. Mass-market cruise lines have been increasingly adopting a model reminiscent of budget airlines: offer a low base fare and present a slew of irresistible amenities at an additional price.

On Norwegian Prima, mini-golf costs $10 per person, while the VR arcade sets guests back $29 for one hour.

On Royal Caribbean's Icon of the Seas, mini-golf is free! But walk slow if you decide to spend money on the ship's part-agility, part-ziplining course. It costs $49 to participate — and could be completed in a minute or so.

But if you're a pushover who easily gives into temptation, be sure to develop a backbone before you cruise with Carnival.

If you don't, mai tais and movie popcorn costs could add up quicker than expected.