Gorges de la Falaise
On a length of about 200 metres the river Falaise flows through a canyon some ten metres deep and 1-3 meters wide. You can discover the canyon by a combination of walking and swimming. The canyon is on private property, hence the fee it also pays for the guide. Be aware that some parts of the route can only be crossed by swimming, so you should wear swimming gear no jeans, shirts, not even hats. However, you need to wear hiking shoes no flip-flops etc. as the hike goes over slippery stones. You can rent appropriate shoes at the entrance. Note that the guide might be able to carry small cameras, but don't bring mobile phones, huge cameras or other stuff. You can leave your clothes, wandering gear, electronics etc. at the hut where the guide is waiting.
For European people coming from an EU country, working in Martinique isn't a 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 high. But if you work in the health sector doctor, nurse, it will be much easier.
Voluntary service: Volontariat Civil à l'Aide Technique VCAT. Only for EU/EEA-citizens. 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.