Answer
Chiang Mai is an inland northern Thailand destination, so it does not have local beaches or offshore islands. For a water-focused day around Chiang Mai, compare waterfalls, hot springs, riverside areas, hotel pools and lakes; for a genuine beach trip, plan separate travel to southern or eastern Thailand.
Practical Chiang Mai planning note: Check weather, road conditions, fitness requirements, footwear, insurance and the provider's safety practices before setting out. Mountain conditions can change faster than conditions in the city, and mobile coverage may be limited in some areas. Chiang Mai is inland; beach and island experiences require travel to another region, while local water-based alternatives include rivers, lakes, waterfalls, pools and hot springs.