Get a go-signal from your Pedia. It’s also better to wait for baby nearing 6 months old; if you can wait a little longer, 6-12 mos may be best.
Keeping a checklist on all essentials (phone can be handy) gives you enough window to calmly prepare. Side note: double the extra clothes for your lil’ swimmer.
Always apply the 30-minute rule in the water; if baby starts to shiver before your allotted time ends, remove from water right away.
Use a baby-safe sunscreen — preferably with a broad spectrum. But don’t just rely on the application, still, avoid direct sunlight.
Let your sunny-sunshines wear shades with UVA & UVB protection. Buying them regular sunnies won’t help in providing defense from the sun’s glaring light.
Have a whale of a time, but always be on guard.