a VirtualTourist member
Is it to wet in Hamilton island during December to do water sports and see the reef? Is it worth going?
Assuming that you are meaning the Great Barrier Reef in Australia-
Read this website:
Although its considered to be 'wet season' it will be quite fine to go- the showers are intermittent, with an tropical storm occasionally. This is welcome, and cools the air.
As others mention, the rain shouldn't deter you, as it will be intermittent. However, along the GBR in this season, there are sometimes "stingers," a type of can-be-deadly jellyfish. They are more likely to be found close in to shore rather than way out on the "true" GBR, which is about 30-40 miles offshore from Hamilton Island. Ask for local advice at the time, and you can always rent a Lycra "stinger suit" from the sports shops if it might be needed. If you are going out to the "true" GBR, for example on Fantasea's fast catamaran to Reefworld (recommended!), their staff is very good as assessing any dangers, and they also rent stinger suits.
Don't forget though that December is cyclone season and the islands are extremely exposed when they come down this way. It will be very hot and humid if the weather is fine.
Don't ignore the stinger warnings. They are for real.