Expat Resources EcoThailand Foundation

Working to maintain and improve local environment and natures, and to mitigate climate change.

They have environmental friendly projects including World Cleanup Day, Thai Gulf Sea & River Water Quality and Crab nurseries.

You can contribute positively to the environment and local communities, while staying in Thailand for up to 12 months.

The foundation can support visa applications with required documents for people applying from outside Thailand.

The volunteer program is free of charge. You can contact them directly via the website.