Mari is a 20-year-old sea witch living in Positano in 1821. Distinguished by her unusually red hair, she serves as the reluctant leader of her village's coven. Despite her formidable maritime magic, she secretly harbors a deep resentment for the sea following painful family tragedies. Weighed down by her responsibilities to her community, she longs for a different life away from the Amalfi Coast.

Haven is a 35-year-old American nautical archaeologist driven by a profound dedication to her career. Following in the footsteps of her late father, she brings her scientific expertise and strong ethical compass to Project Relic. Pragmatic and rational, she dismisses local superstitions about the Amalfi Curse in favor of empirical data and hard evidence.

Holmes is an American sailor working aboard the Aquila, a ship owned by the powerful Mazza brothers. Bearing the callouses and tar stains of his trade, he is a dedicated and ethically minded man who deeply disapproves of his employers' cruel methods. His primary motivation is his devotion to Mari and their shared dream of a life together.

Enzo is the 39-year-old owner of a scuba diving business in modern-day Positano. Having weathered personal and financial hardships, he has adopted a resilient, joyful approach to life. He prioritizes his business but provides a charismatic, lighthearted balance to Haven's serious and academic nature.

Matteo is the ruthless head of the Fratelli Mazza shipping company in Naples. Notorious throughout southern Italy, he operates an unscrupulous business empire that relies on smuggling, piracy, and the cruel treatment of his crews. He is driven by an insatiable greed that threatens Positano and its unique inhabitants.

Conrad is a wealthy retired rescue swimmer and an affluent treasure hunter. As an old friend of Haven's late father, he presents himself as a supportive mentor figure. However, his deep-seated greed and desire to claim valuable historical artifacts for himself often put him at odds with proper archaeological protocols.

Corso is an affluent distant cousin from Rome who is betrothed to Mari. Arrogant and indolent, he views marriage as a transactional arrangement and frequently boasts about the luxurious life he intends to provide. His presence represents a significant social obligation for Mari's family.

Massimo is Matteo's younger brother and partner in their corrupt Naples-based shipping enterprise. He shares his brother's pointed chin, broad shoulders, and viciously greedy worldview. He readily participates in illicit schemes to expand their fortune.

Mal is a skilled nautical diver and Haven's close friend. As the dive marshal, she is responsible for the team's underwater safety and logistics. She is fiercely loyal to Haven and provides pragmatic advice when workplace complications arise.

Savina is Enzo's mother, an older woman living in a centuries-old villa in Positano. Grieving the recent loss of her daughter, she is deeply protective of her surviving child. She is blunt in her opinions about the local tourism industry and holds strong hopes for her son's future.

Imelda is Mari's mother and the former leader of the Positano sea witches. Her mysterious disappearance twelve years prior left a profound emotional scar on Mari. The event shaped the young woman's fraught relationship with her maritime heritage.

Ami is a member of the Positano sea witch coven and Mari's best friend. She provides emotional support and serves as a reliable confidante for Mari. She helps her friend manage the strict rules and heavy responsibilities governing their hidden community.

Dante is Ami's husband and a resident of Positano. He is a fiercely protective family man who immediately springs into action to defend his loved ones when danger approaches the village.

Cleila is Mari's stepmother. She helps manage the household in Positano. She represents part of the domestic structure Mari feels responsible for protecting.

Paola is Mari's 19-year-old stepsister. She lives in the village alongside Mari. The two occasionally experience friction due to their differing responsibilities and social prospects.

Lia is a six-year-old sea witch in training. As the daughter of Ami and Dante, she represents the vulnerable younger generation of Positano that Mari is sworn to protect and educate.

Pippa is a young sea witch learning her craft under Mari's guidance. Eager and observant, she is part of the small community of women entrusted with Positano's safety.

Vivi is a sea witch and Pippa's mother. She participates in the community's defensive measures and faces the same perils as the other women harboring magical secrets.

Mr. Ambrose is Haven's late father and a renowned nautical archaeologist. His lifelong dream of making a major discovery in the Li Galli archipelago drives Haven's current expedition and instills her with a deep love for the ocean.

Gage is the CEO of the Heritage Protection Institute. Focused heavily on public relations and liability, he controls the financial backing for Haven's archaeological work and frequently applies corporate pressure to the team.

Quinto is the first mate aboard the Aquila. He acts as a harsh enforcer for the Mazza brothers, fiercely maintaining discipline and ensuring the company's shady operations run smoothly at sea.

Sofia is Mari's younger sister whose tragic drowning two years prior deeply affected the family. Her death intensified Mari's hatred for the sea and desire to protect her remaining loved ones.