Try to avoid any dark lanes, and always be careful not to leave your bag unattended. Swimming alone on isolated beaches is not advisable. If you sail, avoid bringing valuables; if you have no choice, become adept at finding great hiding places.
There is some social activity along a secondary road behind Beau Vallon beach left from the Boathouse restaurant, but locals mostly seem content to admire their flashy cars and mostly ignore passers-by.
There are newly instituted tourist police stationed at every beach on Mahe and are easily recognizable by their blue or white golf shirts, with a tourist police badge sewn on.
They are very friendly and more than willing to help keep a good eye, even though you may not see them. They are honest and freely offer advice. Potential thieves are obvious mostly due to lurking and just stand out from the locals and tend to hide just off the beach or across the narrow streets near more out of the way beaches. Jail terms are stiff and are strictly enforced since the island makes lots of money from tourism.
Chikungunya virus is a disease spread by mosquitoes, and causes flu-like symptoms. It is increasing in concern and although it is rare to die from it, the joint pain it causes can last for months. Insect repellent can help deter mosquitoes but not much else can be done as a precaution. The disease is native to East Africa and occasionally is introduced and quickly eradicated.
Tap water is safe to drink in most areas of the Seychelles, but water quality is variable in undeveloped areas. It is recommended to drink bottled water only and to avoid bodies of fresh water like lakes, rivers, ponds, etc.