Journey to the River Sea

Maia is an orphan and the main character of the book. Bright, passionate, adventurous, determined and resourceful, Maia has great ambition and a talent for music. She used to live and study in a boarding school in England, called "Mayfair Academy for Young Ladies"; all fees were subsidised by her parents' trust fund. She journeys to the Amazon to live with her relatives, the Carters, who exploit, neglect and abuse her, only keeping her under their roof for the sake of her parents' money. She grows close to her governess, Miss Minton. She also forms remarkably close bonds with both Clovis King and Finn Taverner, who are, if in different ways, in lonely and vulnerable situations similar to her own. Maia is excited and mystified by the unexplored Amazon and deeply cares about it once it becomes her own home.

Clovis (Jimmy Bates, as Clovis is his stage name) is an impoverished boy actor who dreams of going home to England. He has a mishap in Manaus and leaves the acting troupe as they fall into debt and are arrested. Later, Clovis takes Finn's place as heir at Westwood in England, convincing detectives of the false identity. He is reunited with his foster mother who persuades him to reveal his true identity. Clovis tries to reveal his identity on several occasions—one of which results in disaster, and Clovis remains heir to Westwood. He has feelings for Maia, asking Finn whether he can "have Maia when she's grown up." He ends the book living like the wealthy heir Finn Taverner. Clovis is kind and sensitive, yet his insecurities and anxiety (characterised by his frequent homesickness and tears) are mistaken at first for cowardice. The book concludes with him having found courage, using his acting talent to succeed in his dream of reaching England and his mother.

A half-English boy who is the true heir of Westwood (his father's aristocratic home). He had a dog called Rob. Loathing to leave his life on the Amazon, however, he spends a long period of time evading those who wish to return him to England. He befriends Maia and comes to trust her completely. With her help, he persuades Clovis to take on his identity and become the heir of Westwood in his place. Afterwards, he sails down the rivers on the Arabella along with Maia looking for the Xanti (his mother's tribe) and succeeds. At the end of the book, he, Maia, Professor Glastonbury and Miss Minton all remain in the Amazon, referring to it as "home". It is implied that Finn too has romantic feelings for Maia, most notably when Clovis asks if he can marry Maia when she's grown-up and Finn's smile vanishes and he answers 'NO!'. Finn desires to become a herbalist or a doctor that treats patients with plants and roots found in the wilderness rather than medicine.

Mrs Carter is the twins' (Gwendolyn and Beatrice) mother and Mr Carter's wife. It is clear she only took Maia in for the money that came with her. She uses this to buy various varieties of insect repellent as she is shown to hate bugs. She is also greedy and demonstrates signs of increasing mental instability towards the end of the book. When she gets the money Maia brought she doesn't spend it on Maia's needs such as piano lessons for her she just uses it to buy herself clothes and her daughter twins dresses. She is in debt, and all the other families living in Manaus despise the Carters. When her house is set on fire, she goes to live with a distant relative, who turns Mrs Carter into her personal maid.

Mr Carter is the twins' father. He is in debt in Manaus and is wanted for fraud in England after embezzling the bank where he worked. He is shown to be manipulative and has an obsession with collecting famous peoples' glass eyes. At the end of the novel, he is sent to prison in the Amazon after failing to pay workers and loan sharks. He also gets taken to prison by Gonzales. Mr Carter is a very mysterious man; he doesn't really care for his family and spends all day in his messy office obsessing over his collection of eyeballs. He loves his collection of eyeballs to such an extent that when the Carters' home caught fire, he chose to retrieve his collection of eyes from his office instead of helping Maia from the burning house. When questioned by Miss Minton at the hospital he claims that he tried to get to Maia's room but the fire prevented him from reaching her.

Miss Minton is the governess of Maia. She is reserved. She is introduced as a "tall, gaunt woman" wearing black clothing and frightening accessories such as a hatpin modeled after a Viking spear and a steel, beaked umbrella. She is kind and concerned with routine and proper learning, encouraging Maia to study Portuguese, for example, in the empty dining room of a ship caught in a storm, or asking Finn to continue his Latin studies whilst in the Amazon rainforest. She loves reading books, particularly Shakespeare. A close friend of Bernard Taverner, she is revealed to be the maid who helped him escape his abusive household and reach the Amazon when they were younger. This is realised as her friend named his boat after her: the "Arabella". Miss Minton takes the job with the Carters in order to follow her late friend's journey to the Amazon. She is extremely intelligent, having been revealed to have knowledge of all the plots the children concoct but allowing them to take place. She has a witty and dry sense of humour, and is cunning, using deception and acting in order to protect the children from unkind and corrupt individuals, such as the detectives. Miss Minton grows to love Maia and treats her like her own child. She finally manages to persuade Mr Murray to let her and Maia live together in the Amazon. Furthermore, she seems to find romance with Doctor Glastonbury, a naturalist, and Bernard's close friend. He eventually proposes to her, but she is not certain of her suitability to marry.

Trapwood and Low are two detectives who search for Finn (who is the legitimate heir) on behalf of Aubrey Taverner. They are greedy, hoping only for money in exchange for their work, and are clumsy and unkind in their attempts to discover the boy. Two unwittingly comedic individuals, Mr Trapwood being harsh and tall and Mr Low being short with a high pitched tone, they wear only black suits despite the weather. Whilst being led astray from their mission by residents of Manaus and the Amazonian Natives (all of whom despise them, being friends of Bernard and Finn Taverner), they befall a series of comedic misfortunes. Their racism towards the Natives is also their downfall, as they are mocked by the tribes, refuse to change out of British attire and therefore overheat, and are easily deceived by Finn's charade towards the end of the novel due to their irrational prejudices.

Miss Emily is Maia's teacher in her boarding school before Maia leaves to Brazil. She is very close to her sister Miss Banks and has a very storng bond with her. She is comforting as she lets Maia not know about her parents but instead comfort her. She is in her 40s and is very kind. She helped Maia before her way to Brazil