Short answer
São Miguel is the best island for both surfing and canyoning. It has consistent waves, especially in the north coast spots like Ribeira Grande and Mosteiros, and canyoning is popular in the volcanic valleys, with guided tours available. Terceira and Faial also offer some surfing, but São Miguel has more infrastructure and schools. For canyoning, São Miguel's Ribeira dos Caldeirões and other spots are top choices. Always go with certified guides and check conditions. Confirm with local operators for seasonal availability and safety guidelines.
General information, not legal or tax advice. Rules and amounts change: confirm with official sources.