Unless they're ill and purposely strand on a beach somewhere, the great cetaceans - whales, dolphins and their air-breathing ilk - never have much of a reason to haul themselves ashore. As a matter of fact, none of the behemoths of the deep oceans are ever seen on land whilst in perfect health.
Sea turtles are the exception.
Like all turtles, they reproduce by laying eggs, which must be deposited in terra firma to incubate. Every summer, female marine turtles hit the beach like Allied landing craft at Normandy. But they do it individually - turtles do not school, nor do they maintain any sort of familiar unity. And they do it late at night, when the beach is dark and quiet.
Loggerhead sea turtles nest on Tybee Island from May through August, crawling from the surf 50 feet or more to get past the tide line to dry sand. It's a laborious process, and for a creature that can weigh 350 pounds or more, exhausting. She digs the nest cavity with her rear flippers, which she can't turn her head to see, then drops the eggs - up to 100 at a time - and covers the hole, again without the benefit of a flexible neck or body. It's all done by instinct.
When everything has been camouflaged to her primal satisfaction, she hefts around using the massive swimming fins up front, and crawls back to the safety of the ocean.
It's one of marine biology's most fascinating mysteries.
"There's so much that we don't know about these turtles," says Tammy Smith, who's licensed by the Georgia Department of Natural Resources to look after Tybee's loggerheads. "They're very rarely seen. And they have been doing this for millions of years."
With its five miles of sand, Tybee is not one of the state's busiest beaches, in terms of nocturnal turtle activity. There are 13 barrier islands under DNR's care, and it falls way short of, say, Cumberland, which has logged more than 600 turtle nests since this year's season officially began.
As of July 30, Smith and the volunteers who work for her as the Tybee Sea Turtle Project have documented 21 nests on Tybee.
"Not all parts of the beach are good nesting habitat," Smith says. "We're also populated; us and St. Simons are well-developed islands, and many of the other islands are undeveloped. Lighting is an issue. We have a lot of people on our beach, throughout the day, all hours of the night, throughout the morning.
"And we're not a natural beach. Tybee is re-nourished every seven eight years, so technically we're not a natural nesting habitat."
OK, so 21 nests may not sound like much. But in the two decades since biologists began keeping data on Tybee turtle activity, it's a record.
The previous high count, in 1996, was 14 turtle nests.
Do the math - it takes 50-70 days for the eggs to hatch, so if all goes well, Tybee will have sent as many as 2,100 two-inch baby loggerheads scurrying into the Atlantic by October. And nesting season still has a few weeks to go.
Nature being nature, not all the eggs will hatch. The tiny baby turtles can fall victim to ghost grabs, seabirds and voracious fish.
And man-made lighting on the beach can disorient them, as it does the adult females. Hatchlings have turned up in swimming pools, and been squished on beachfront roads. That's why most coastal cities have ordinances against strong beach lighting during the summer months.
JULY 27 IN SOUTH BEACH: (click to watch video)
For Smith, Tybee's record-breaking summer is a small but substantial victory. "If it was just Tybee," she says, "then I might could say it's some of the things we've done, as far as out ‘Lights Out' campaign, just educating the public.
"However, it's statewide that everything is high. So I feel, and after talking with DNR, that it's conservation efforts, and fisheries-management regulations. Temperature could definitely play a role - we had a very warm winter, and the turtles may not have gone as far off as they normally do when it gets colder.
"But no one really knows for sure what's causing this increase."
It is against state and federal law to molest, harass or possess sea turtles, their eggs or hatchlings. For more information, see tybeemarinescience.org/sea-turtle-project