The attack raises fresh concern about tourist safety in Thailand, which hosted a record 29 million visitors last year.
Police had the five Cambodian suspects in the attack on Koh Kut reenact the crime, a standard procedure in Thai justice.
Irate residents tried to attack the men but police pushed them away. Police say they will press charges of rape and conspiracy to assault against the five, whom they claim have confessed their involvement.
A director of the hospital where the victims were taken after the Saturday night attack said their condition has improved, with the most badly injured one moved out of the intensive care unit yesterday. The women, ages 57 and 28, are mother and daughter.
More From This Section
The two men, one from the same family, are 30 and 29 years old.
Trat province police chief Maj Gen Nopparat Rintapon said the five suspects had jumped off their anchored fishing boat and swam to Koh Kut after they had been drinking.
Two of them met the French tourists and began talking to them, when the other three came running from the brush where they had been hiding and attacked them with knives and sticks, slashing one of the men badly while the other was able to escape and run to a nearby hotel for help.
The other two were arrested yesterday afternoon at a border checkpoint when they tried to cross into Cambodia.
Tourist safety in Thailand has become a major issue since the murders of a British man and woman whose bodies were found on the southern Thai resort island of Koh Tao in September 2014.
The woman had also been raped. A court sentenced two Myanmar migrants to death in December in a case battered by concerns that the convicted men may have been scapegoats, and that police did not conduct a competent investigation.