Jack Davies, known to friends as Jay, had been travelling for three years when he died at Ko Phi Phi near Phuket.
Officials say the cause of his death is still being investigated and government officials are supporting his family.
In a statement, his parents Christine and Jonathan Davies, who live in Llanelli, south Wales, said: "He was a lovely boy and everybody loved him."
Mr Davies had been working and travelling in Thailand since 2011.
A Foreign and Commonwealth Office spokesperson said: "We are providing consular assistance to the family at this difficult time."