Search efforts are underway, and officials have asked fishermen, boat operators and residents along the coastline to be on the lookout for her. Authorities say Waddell, 44, was last seen Wednesday on a beach along the southern coast of the Caribbean island.
As loved ones wait for answers, Waddell's husband, Cailen Waddell, shared details about the woman he describes as compassionate, outgoing and eager to help others.
"My wife is a loving, free-spirited person," he said. "She can make friends with anyone, and she often did. She placed great value in her intuition about people and was always willing to help someone."
A neighbor described Waddell as "bubbly, bubbly, super friendly," and said she shared a flier on social media in hopes of helping the search.
"I'm really, really glad to see that there's so much support. And it looks to be like a really great coordination of efforts between local and international authorities," said the neighbor, who did not want to be identified. "I'm really sad about what happened. But I am also hopeful."
The circumstances surrounding Waddell's disappearance remain under investigation. Search crews and local authorities are working to locate her, while family members continue to spread awareness in hopes of generating leads.
Waddell is a physical therapist in Cary and also works as an instructor at Aradia Fitness.
The studio's owner posted a message on social media saying, "We are hoping and praying for her safe return."
Chris Bradley, a security consultant with The Scout Solutions Group, said missing-person cases involving large bodies of water can quickly become more complex. "The scope of that investigation immediately broadens because the ocean is a big body of water," Bradley said.
Bradley noted that the involvement of maritime authorities could play a critical role in the search effort.
"One of the things that I've read already is that the Coast Guard was notified, which I think is huge," he said.
He also pointed to another challenge investigators may face: the availability and scope of local rescue resources.
"Not knowing the resources that Grenada has as far as, do they have water rescue?" Bradley said. As search efforts continue, family and friends are urging anyone with information about Waddell's whereabouts to contact authorities.
The U.S. State Department told ABC News it was aware that Waddell was missing in Grenada and was assisting the family with filing missing persons reports. The agency declined to comment further, citing privacy.
For now, loved ones remain hopeful that increased awareness and continued search operations will help bring answers in the days ahead.
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