Now that the popularity of Brooke is waning, and surname style variant Brooks is on the rise, Brook seems live a newly fresh nature-inspired option.

Brook

It's a nature name evocative of rushing waterfalls. But also a dishwashing detergent. 

Cascade

Even though in the past Clyde may have been identified as half of the infamous outlaw duo with partner Bonnie Parker—especially after the 1967 movie in which he was played by Warren Beatty—Clyde has always had an element of jazzy cool that could overcome all the rest.
 The name relates to the River Clyde that runs through Glasgow, Scotland. It was a Top 100 name in the US through the 1930s, and has made a comeback in the last few years, reentering the Top 1000 in 2013.
 Clyde Griffiths was the doomed protaganist of Theodore Dreiser's 1925 novel An American Tragedy. In the field of sports, basketball Hall of Famer—and later Dancing With the Stars participant—Clyde Drexler was known as Clyde the Glide, and Walt Frazier's nickname was Clyde. Catherine Keener and Dermot Mulroney have a son named Clyde.

Clyde

Cove is an up-and-coming nature name whose cool sound and peaceful image saw it rising for both sexes... until COVID-19 hit. It remained steady in use for boys in 2021, but actually increased for girls, although it remains a seriously rare and distinctive choice for either gender. 

Cove

Douglas, and more particularly its nickname, Doug, had a real romantic swagger in the 1950s and 1960s dating back to swashbuckling Douglas Fairbanks, but today is more likely to conjure up your mom's prom date. Originally a Celtic river name, it became attached to a powerful Scottish clan, renowned for their strength and courage. In its earliest incarnation, Douglas was used equally for girls and boys.
 Douglas has been on the popularity list for as long as US records have been kept, for a considerable period in the Top 100, often used to honor World War II General Douglas MacArthur.

Douglas

Drina

Dvina

Jezero

Laiken

Evocative modern unisex choice brought into the spotlight by actress Lake Bell. 

Lake

This is an unusual surname and geographical name of medieval Scottish origin that might serve as a possible alternative to the aging Keith, though it's a bit tough on the tongue. More popularly spelt Laith in Scotland itself, which happens to correspond to an Arabic name meaning 'lion'.

Leith

Lynn arrived in the 1940s, spinning off from the wildly popular Linda, to become a top midcentury middle name. Now, Lynn's in limbo. 

Lynn

A happy medium between the weighty Maximilian and the laid-back Max, Maxwell is one of the most classic and attractive <a href="https://nameberry.com/list/428/scottish-baby-names">Scottish names</a>. Early influences on the name's revival include Maxwell Smart of the television show, and then movie, Get Smart, and the Beatles song about Maxwell's Silver Hammer.
 Lance Armstrong chose it for his son, but there was a sharp and unexpected gender switch when both Jessica Simpson and Lindsay Sloane both chose it for their daughters. Still, in the US baby boy Maxwells outnumber baby girls 50 to 1.

Maxwell

Maringa

Maritsa

Morava 

Among a small shower of rain-related names, this pure version can have a cool, refreshing image. 
 Richard Pryor named his now-grown daughter Rain, and Rain is also one of the nature-named Phoenix family siblings. More recently, 24 actress Marisol Nichols named her daughter Rain India.
 Rain also makes a nice nature middle name--Brooke Burke called her daughter Heaven Rain.
 If you want to embellish this simply spelling (and alter the meaning), you might also consider Raine, Raina, Rainn, Rayne, Reine or Reign, the middle name of Willow Smith. Or you could take the Holly Madison route all the way to Rainbow.

Rain

Actress Jaime King gave her son Leo the middle name Thames, for the famous London river where she and her husband Kyle Newman were married.  Thames is pronounced tehms, not necessarily common knowledge in the US. The etymology of the word Thames is uncertain, and may mean dark but more likely stems from an ancient word for river.

Thames

Tarni 

Vistula

Highly unusual as a baby name for either gender, Yarrow is an herb that grows wild and has long been used for its medicinal property. It's named for the mythical Achilles, who was said to carry yarrow into battle.

Yarrow

undefined's list "Water baby names " of 23 great name ideas: Brook - Yarrow!

Water baby names 

Row, row, row your boat down this list full of pretty water names. 