Scuba diving and snorkeling. There is an amazing assortment of tropical fish, even in water less than one metre deep. For those who can't swim, glass bottomed boat trips are on offer.
There are many festivals to attend to in Guadeloupe. In Guadeloupe they call them "parties on the street". They use colourful ribbons and tie them round their wrists to resemble the colours of all the nations. Their parties last all through the night until the early morning. They sometimes call them "swatson".
For European people coming from an EU country, working in Guadeloupe is allowed without problem. If you're from outside the EU, you will probably need a work permit - check with the French Embassy in your country. Do not forget though that the unemployment rate is around 28%. But if you work in the health sector doctor, nurse, it will be much easier. Else you could find a job in bars, restaurants, and/or nightclubs. The better is to have a precise idea of what you want to do, inform yourself and prospect before going there.
Voluntary service: Volontariat Civil à l'Aide Technique VCAT. Conditions: you must be French or from another EU-member state or a country belonging to the European Economic Area. You must be over 18 and under 28 years old inclusive. You must not have had your civic rights revoked by a court or have been convicted of certain offences. VCAT (http://www.outre-mer.gouv...), Préfecture Guadeloupe (http://www.guadeloupe.pre...).