Each operator sets its own, and rough seas can raise it on the day. The tour page carries the current rule.
A compact one may get on a big boat. It will be useless on sand, stairs and the transfer van. Ask first, and plan to carry the child.
A big boat or a private charter beats a packed speedboat most of the time. Weather and the operator policy still get a vote, as does your own toddler.
Families do this trip every day of the week. That does not make every boat right for every child. Ignore the family-friendly sticker and look at four things instead: the crossing, the heat, the stairs and how long the day runs.
Room to wriggle is worth a lot on a big boat. A speedboat cuts the crossing short but bounces more. A small-group boat means less queuing, which is its own kind of mercy with tired kids.
Both headline viewpoints involve climbing. Emerald Lagoon is short and steep; Koh Wua Talap is a proper haul. One parent can usually stay down at the bottom with a child, as long as you clear it with the guide.
Three questions before you book: can a child share your kayak, what is the minimum age, and can we sit this one out? Answers vary per operator.
Serious sun cream. Dry clothes. Shoes that stay on wet rock. Any medicine you already use. And more snacks than seem reasonable, because lunch can land later than a small stomach expects.
