The Zhejiang Museum of Natural History gives Hangzhou a useful indoor counterweight to West Lake, tea villages, and temples. Its galleries cover dinosaurs and fossils, minerals, local ecology, and animal life, with enough large specimens and visual displays to keep the visit lively even if you do not read much Chinese.
It is strongest as a family stop or rainy-day museum, but there is real regional context here too. Zhejiang's landscapes run from coast to mountains, and the museum helps make sense of that variety before you head out to the lake, wetlands, or surrounding hills.