Kamsuan Samut (Thai: กำสรวลสมุทร, pronounced [kām.sǔan sā.mùt]), translated into English as Ocean Lament, is a poem of around 520 lines in Thai in the khlong si meter. It concerns a man who leaves the old Siamese capital of Ayutthaya and travels in a small boat down the Chao Phraya River and out into the Gulf of Thailand. Along the way he laments over his parting from a lover who he calls Si Chulalak, perhaps the name of a royal consort. The reason for his flight and his destination are not explained. The extant poem ends abruptly, although there might have been a longer variant. The work is considered a precursor or pioneer of the nirat genre of Thai poetry. The authorship, dating and original title of the poem are unknown and have been subjects of academic debate. The poem was once attributed to a court poet named Si Prat in the reign of King Narai (r. 1656–1688), but this is now considered doubtful. The poem was first printed in 1950. It is considered a gem of old Thai literature because of the intensity of the poet's expression of loss and the elegance of the verse.