This can be a problem since basic scuba gear weighs around 15Kg which does not allow for much else. If you also carry underwater photography equipment your allowance is quickly used up. For this reason, cylinders and weights are usually provided on site and equipment hire is also available. Diving knives must be packed with the rest of your diving gear and carried in the hold. Pony bottles and emergency cylinders must be completely emptied and also carried in the hold.
Many divers travel abroad to dive on coral reefs which are one of nature's wonders.
Nearly all coral reefs are in the tropics which means that the local climate will be hot. Divers must take care to avoid dehydration and desist from sunbathing immediately following a dive both are predisposing factors in decompression illness. Most tropical dive locations are in and around developing countries with poor standards of hygiene etc. Because of the repeated immersion in sea water, divers are prone to ear problems. Infections can result from sea water trapped inside the ear canal.