While staying with a friend in Surat Thani she brought me to see her mums "shell farm". Everyday the sea is farmed and brought down the river to a small fisher village where the muscles, crabs, lobsters, cockels etc. are seperated before being forwarded to be sold in Tescos.
Surat Thani has an active night market which is a good place to wander around. There is a lot of local food for sale.