There are silly questions about Hawaii, and then there are questions where the answer isn’t quite as readily apparent, where our regional differences might baffle the rest of the world. Just because it’s stuff that we take for granted doesn’t mean there isn’t a good explanation. Here, we hope to clarify some of the wonderful, unusual and sometimes just plain illogical things about Hawaii.

1. “Why does everyone take their shoes off to enter a house in Hawaii?”

If you’ve ever been to someone’s home in Hawaii for a gathering, you’ve probably noticed the rows of slippers and shoes that grace every entranceway. It doesn’t matter what type of shoes you have, or even if you’re wearing slippers (flip-flops to the uninitiated, see question No. 3), you generally take them off before setting foot in the house.

The custom came from a mix of cultures, such as Hawaiian, Chinese and Japanese, that took hold during the early plantation days. It shows respect to the owner of the house by keeping their home clean and not tracking dirt and germs inside, especially if there’s a baby or toddler crawling around on the floor, but on an emotional level, removing your shoes also means it’s time to relax and join in the party. Just don’t break the cardinal rule: Always leave with the same pair of shoes you came in with!

2. “If someone lives in Hawaii, they’re Hawaiian, right? What’s the difference?”

This is an incredibly common misconception that follows different rules from the rest of the United States (Californians, Oregonians, etc.). It goes back to the fact that Hawaiians are themselves a specific people of Polynesian origin with their own culture and traditions.

Although Merriam-Webster’s Dictionary defines Hawaiian as “a native or resident of Hawaii,” other resources have made a change over the years to reflect that Hawaiians are people only of native ancestry. Federal documents now use “Hawaii residents” in place of “Hawaiians,” and, in 2005, the Associated Press updated its stylebook in the same way, to avoid erroneous instances, such as when Michelle Wie, of Korean ancestry, was described as a Hawaiian.

To this day, it is frowned upon to call someone without Hawaiian blood a Hawaiian. Individuals born in the Islands without Hawaiian blood are generally referred to as locals or residents.

3. “Why do people in Hawaii call their shoes ‘slippers’ instead of ‘flip-flops’”?

In Hawaii, locals don’t wear “flip-flops,” nor do they wear “thongs.” What you should understand is the deep island pride in the iconic rubber slipper, also known as the “slippah,” which traces its roots back to the Japanese zori (traditional flat sandals made of rice straw or plant fibers) and came into popular use in Hawaii after World War II. Leading the way was Scott Hawaii. Founded in 1932, Scott Hawaii began as a manufacturer of boots for workers in the sugar plantations. During the war, however, materials were in short supply so the company transitioned to casual sandals.

Although slippers in the rest of the United States imply fuzzy bedroom footwear with optional bunny ears, in Hawaii, the name appears to be a usage that grew from Hawaiian Pidgin English. To a Hawaii local, a slipper signifies comfort and relaxation, and just the basics. When the temperature stays as tropical all the time as it does here, you don’t need shoes outside, but a slippah, as some locals pronounce it, is practical for so many things; from wearing on your feet as protection from hot sand, rocks or glass on the ground to propping up a table or killing a cockroach.

Side note: You should be aware that there are different classes of slippah. Going to the beach? Wear your regular slippahs. Going to a house party, or a social event? Bust out those fancy slippahs.

4. “Why are there interstate highways in Hawaii?”

That’s a good question, since the literal definition of an “interstate” should be a road between two states, right? But the answer lies with its government classification as any highway that receives federal funding. In 1960, President Dwight Eisenhower signed The Hawaii Omnibus Act, which removed the limitation that the Interstate System be designated only within the continental United States. Although Hawaii’s interstate highways may not be connected to any other state, they are built to interstate standards, constructed to support the weight of tanks and military transport vehicles and designed for speeds of 50 to 70 miles per hour, as part of the Dwight D. Eisenhower System of Interstate and National Defense Highways.

5. “Why is the water in Hawaii so clear?”

When it comes to gorgeous beaches, Hawaii is picture perfect. For one, there is less runoff from shore in some places, and the soil that does end up in the ocean tends to be volcanic or sand and coral-based, which sinks quickly and doesn’t stay suspended in the water. Additionally, natural ocean currents bring a constant supply of fresh ocean water to our shores, while our coral reefs protect us from the stronger currents that would displace the waters near the beach.

Grieg Steward, a professor at the University of Hawaii’s Department of Oceanography adds, “The very warm surface waters in tropical areas (such as around Hawaii and the Bahamas) are so clear because of very low nutrient concentrations, which limits the amount of phytoplankton and zooplankton.”

6. “Why are Hawaiian words and street names so long and full of vowels?”

It’s because the Hawaiian alphabet has only 13 letters: Five vowels and seven other consonants: H, K, L, M, N, P and W plus the okina symbol, which is considered a consonant. Every word in the Hawaiian language ends with a vowel. You might think that sounds simpler than English, but what it means is that Hawaiian lends itself well to compound words. So, that long Hawaiian word on the street sign might be an entire phrase. Other streets are named after Hawaiian fauna (such as, Hawaii Island’s Niuhaohao, or “young coconut”), stars, natural phenomena (Ala Wai means “water path” or canal) or Hawaiian royalty. The bustling Kalakaua Avenue, Waikiki’s beachside thoroughfare, was named for King Kalakaua, and Liliuokalani Avenue is named for Queen Liliuokalani, the last of the Hawaiian monarchs.

Interesting side note: It is an ordinance by the City and County of Honolulu that “street names selected shall consist of Hawaiian names, word or phrases and shall be selected with a view to the appropriateness of the name to historic, cultural, scenic and topographical features of the area.”

7. “How did Hawaii get so culturally diverse?”

During the 19th and early 20th century, large waves of Chinese, Japanese, Filipino and other various ethnic laborers immigrated to Hawaii to work in the booming sugar plantation industry. Although some laborers left after completing their contracts, the majority decided to stay and intermingled with one another, creating the multicultural mixing pot that is now home to the nation’s largest population of multiracial Americans.

8. “Why are there so many rainbows in Hawaii?”

Hawaii isn’t called the Rainbow State for nothing. One of the beautiful things about being in paradise is that rainbows are everywhere. This is due partly to the geography of the Hawaiian Islands themselves. Our trade winds gather moisture and carry it until they hit a mountain. Lingering sheets of moisture over the mountains mixed with bright sunlight are the perfect condition for rainbows to form—not to mention the salt in the air that helps act as a prism to make the rainbows more intense. You’ll most likely spot rainbows earlier in the morning or late in the afternoon.

9. “What are those long furry creatures that I see running across the road? Are those ferrets?”

Oh, those “Hawaiian ferrets.” The furry critters you often see moving incredibly fast out of the corner of your eye aren’t rats, or ferrets, or cats or squirrels. They’re actually an invasive species called the Small Asian Mongoose, imported in the 1880s to sugar mills on Hawaii Island, in the hopes that the weasel-like carnivores would eat the rats damaging the sugarcane. Afterwards, those mongooses’ descendants were shipped to plantations on Oahu, Maui and Molokai, where they thrived with no natural predators and did incalculable damage to the native bird species, nearly driving the Native Hawaiian goose, the nene, to extinction.

In the Honolulu Evening Bulletin, December 1895, Commissioner Marsden wrote: “The next importation was by the Hilo planters, who in 1883 sent Mr. Jonathan Tucker to Jamaica in the West Indies to procure mongoose for them. Mr. Tucker returned with 75 mongooses in good condition, which were liberated in the cane fields in Hilo. They soon increased in numbers and the ravages of the rats correspondingly diminished. The planters of Hamakua, hearing of the good work done by the mongooses in Hilo, decided to import some on their own account.”

By 1916, the Territory of Hawaii realized that importing the mongoose had been a mistake and offered a bounty of 10 cents for each mongoose head. Today, mongooses are still considered an invasive species.

10. “Why is milk (and everything else) in Hawaii so expensive?”

Chances are, if you weren’t born or raised in the Islands, you got sticker shock the first time you saw the price of a gallon of milk. Five dollars or more is the norm, and often it’s more than that. The basic reason why prices on groceries are so much higher in Hawaii is a simple one: It’s the cost of shipping goods 2,467 miles from California to Hawaii. Even local farmers rely on mainland feed for their cattle and must comply with state pricing requirements, which makes it even more expensive to put on shelves than the imported milk.

11. Do I need a passport to travel to Hawaiʻi?

Surprisingly, we get this questions asked a lot. Maybe it’s because Hawaiʻi isn’t attached to the continental United States, or the fact that it’s just so otherworldly over here—in a good way.

While the overthrow of the Hawaiian Kingdom is a truly divisive topic, one that we won’t get in to here, Hawaiʻi is considered to be a part of the United States of America, and is the nation’s 50th state. So, no, you do not need a passport to travel to Hawaiʻi. And continuing on that topic, you also do not need to worry about other factors you’d have to consider with international travel—like getting a SIM card for your cellphone or exchanging USD into a foreign currency—as visiting Hawaiʻi is in many ways just like visiting anywhere else in the states, except there’s way more postcard-perfect beaches and natural beauty.

12. What does “kapu” mean?

If you travel to Hawaiʻi, you may come across a whole bevy of Hawaiian words on signage around the state. For example, many establishments call the men’s restroom kāne (men) and the women’s restroom wahine (women). The use of proliferation of ʻōlelo Hawaiʻi (the Hawaiian language) is really what makes Hawaiʻi such a unique and amazing place to visit, however there’s one word you should absolutely know when visiting Hawaiʻi.

The word kapu (taboo, prohibited, forbidden) carries a lot in Hawaiian culture. For centuries before western contact, the kapu system was essentially ancient Hawaiʻi’s societal code of conduct of rules and regulations. Kapu were strictly enforced, and often times breaking kapu meant the offender received capital punishment—death. In the modern era, kapu is significantly less drastic, however the word is still used to denote sites or areas that are off-limits, sacred or places that should not be tread upon by outsiders. If you see a kapu sign, do not cross it.