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: Approach temples, ceremonies and community events respectfully. Dress requirements, photography rules, access areas and festival arrangements can vary, so follow signs and staff instructions and avoid treating religious spaces as ordinary photo locations. 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.