Make sure you do and know a few things before you go:
The flight time is around nine hours from London, 11 to 13 from Europe and between 90 minutes and 7 hours from Mainland USA.
The Money: The official currency is the Eastern Caribbean dollar, written EC$. It's pegged to the US dollar at US$1 to EC$2.70. You can pay for most things in US dollars as well as EC dollars, though you'll be given change in EC dollars, and establishments normally use a rate of EC$2.60 to $1. Some things, such as hotel rates, and sometimes food and drink in hotels, are quoted in US dollars.
Cash points issue EC dollars.
Foreign Office Advice: gov.uk/foreign-travel-advice/st-lucia
police, fire, ambulance – 911
Most electrical sockets in hotels take three-pin, square UK-standard plugs British travellers don't need adaptors, but Us and european travellers will.
While St Lucia is and feels easy-going and pretty safe place, crime does happen even against tourists. There have been 2 majot incidents in 3 years. In early 2014, a British couple were attacked on a yacht moored off the island, and the husband died in the incident.
In April 2013, armed men robbed a group of cruise-ship passengers at the Diamond Falls Botanical Gardens in Soufrière, and in November 2012 a tourist was assaulted in daylight at Vigie beach, north of Castries.
So you need to exercise caution when out and about, and do be particularly careful on isolated beaches and beauty spots, and at "jump up" street parties. Take the usual precautions with valuables and money.
Local laws and etiquette:
All St Lucia beaches form part of the "Queen's Chain" and are therefore public, though you may run into some problems with recent developments which seek to restrict access to non residents of the resorts.
It's against the law for anyone, including children, to wear camouflage clothing