Detectives in Likoni Mombasa county on Thursday evening arrested three Ethiopian aliens while trying to cross to the Island.
They were apprehended at the newly installed screening areas at the ferry.
Tamasken Hussein Worqu, 23, Samuel Demise,22,and Takatal Petros, 29, will be taken to court on Friday.
Likoni Police chief Willy Simba said the suspects will be charged with being in Kenya illegally.
Adan Abdirahman Abdi, a 28 year-old Kenyan, will be charged on counts of human trafficking, police said.