In the Florida Keys, it’s common for locals and savvy visitors to greet the news of some particularly offbeat happening by grinning and murmuring, “Only in the Keys.”

The four-word phrase is a standard response for people hearing about everything from a parade for dachshunds to mermaids attending a local music festival (FYI, these are both actual things).

Hemingway cat Key West

Each morning, Ernest Hemingway wrote in the studio (in background) behind his Spanish Colonial home in Key West. (Photo by Rob O’Neal, Florida Keys News Bureau)

Along with examples of wonderful wackiness, many other intriguing elements and activities can be enjoyed “only in the Keys” — like the four Key West and Lower Keys suggestions here.

1. Explore the homes of literary legend Ernest Hemingway and former president Harry Truman … on the same day. Key West is home to the Harry S. Truman Little White House Museum, Florida’s only presidential museum, and the Ernest Hemingway Home & Museum, where Hemingway lived and wrote for most of the 1930s.

Truman spent approximately six months of his 1945-53 presidency in Key West, running the country from a roomy West Indian structure that became known as his Little White House. Today visitors can tour it, discovering items including the original piano and poker table (ask about its unassuming “disguise”) used by the former POTUS.

Hemingway’s home and second-story writing studio offer a glimpse into American literary history — and the place where he wrote some of his most notable works including “To Have and Have Not,” which is set in Key West.

Visitors can tour the late author’s Spanish Colonial home, peer into his second-story writing studio and even pet the descendents of his six-toed cat. There are actually about 50 felines living on the property — including a grey-and-white charmer named Mata Hari who often naps in Ernest’s writing studio.

2. Get “starstruck” in the Lower Keys. Spotting major stars in the Lower Keys doesn’t usually mean sighting Johnny Depp, Angelina Jolie or even a random Kardashian.

Instead, when 600 or so “starstruck” people gather for the annual Winter Star Party, their goal is to observe southern constellations, comets and celestial objects in the Lower Keys’ clear night skies.

Lower Keys astronomer

Tedda Howard focuses her massive telescope on Jupiter during a past Winter Star Party in the Lower Keys. (Photo by Rob O’Neal, Florida Keys News Bureau)

The Lower Keys, by the way, are virtually the only place in the continental U.S. where these wonders can be seen — primarily because the region’s southern location, “steady” skies and relative absence of large-scale artificial lighting at night provide world-class viewing conditions.

The annual star party draws professional and amateur astronomers and astro-imagers from around the globe. The next one is set for Feb. 20-26, 2017.

3. Take a “southernmost selfie.” It’s just a concrete buoy replica, and most people agree that its red, black and yellow body isn’t the most picturesque thing in Key West. But every day of the year, many hundreds of visitors line up to have their photos taken beside the Southernmost Point.

Why? Because the ungainly buoy marks the southernmost spot of land in the continental United States. It overlooks the Atlantic Ocean at Whitehead and South streets, and its brightly-painted body bears lettering that proclaims it stands just 90 miles from Cuba. What better place for a selfie?

4. Attend a music festival — underwater. Each July, several hundred divers and snorkelers explore a gorgeous section of the world’s third-largest coral barrier reef during a sub-sea concert in Lower Keys waters.

"Mermaids" play instruments sculpted by a local artist at a past Lower Keys Underwater Music Festival. (Photo by Bob Care, Florida Keys News Bureau)

“Mermaids” play instruments sculpted by a local artist at a past Lower Keys Underwater Music Festival. (Photo by Bob Care, Florida Keys News Bureau)

The Lower Keys Underwater Music Festival spotlights coral reef protection and environmentally responsible diving. Staged by local radio station US1 FM, it’s held at Looe Key Reef, part of the Florida Keys National Marine Sanctuary about 6 miles south of Big Pine Key.

You’ll swim among Looe Key’s vivid marine life and coral formations while listening to music broadcast by the radio station — and piped underwater via speakers suspended beneath boats above the reef.

You might even spot costumed “mermaids” beneath the waves (yes, those mermaids noted earlier) pretending to play quirky musical instruments sculpted by a Keys artist.

Let’s face it — whether you’re in Key West, the Lower Keys or elsewhere in the subtropical island chain, the enthusiastic embrace of eccentricity is one of the area’s greatest appeals. So start planning a trip now to discover why the best vacation experiences can be found “only in the Keys.”