Semi-dry suits thumb|alt=Detail of the zipper of a semi-dry wetsuit, showing one end of an open zipper and the neoprene flaps that cover it on the inside and outside of the suit to protect the zipper, improve comfort, and reduce leakage through the closed zip.|Detail showing zipper attachment, internal flap and cover flap of semi-dry suit. This is not a watertight zipper. Semi-dry suits are effectively a wetsuit with improved seals at wrist, neck and ankles and also usually featuring a watertight zipper. Together, these features greatly reduce the amount of water moving through the suit as the wearer moves in the water. The wearer gets wet in a semi-dry suit but the water that enters is soon warmed up and is not "flushed" out by colder water entering from the outside environment, so the wearer remains warm longer. The trapped layer of water does not add significantly to the suit's insulating ability. Any residual water circulation past the seals still causes heat loss, but this loss is minimised due to the more effective seals. Though more expensive and more difficult to take on and off than a wetsuit (in most cases, a helper will be needed to close the dry-zip, which is usually located across the shoulders), semi-dry suits are cheaper and simpler than dry suits, and in the case of scuba diving, require no additional skills to use. They are usually made from thick neoprene (typically 6 mm or more), which provides good thermal protection at shallow depth, but lose buoyancy and thermal protection as the gas bubbles in the Neoprene compress at depth, like a normal wetsuit. Early suits marketed as "Semi-dry" suits came come in various configurations including a one-piece full-body suit or two pieces, made of 'long johns' and a separate 'jacket'. Almost all modern semi-dry suits are one piece suits, with the zipper usually being across the shoulders on the back, but other arrangements have been used. Semi-dry suits do not usually incorporate boots, and most models do not include a hood, (as creating a good seal around the face is difficult) so a separate pair of wetsuit boots, hood and gloves are worn, as needed. They are most suitable for use where the water temperature is between .
Semi-dry suits thumb|alt=Detail of the zipper of a semi-dry wetsuit, showing one end of an open zipper and the neoprene flaps that cover it on the inside and outside of the suit to protect the zipper, improve comfort, and reduce leakage through the closed zip.|Detail showing zipper attachment, internal flap and cover flap of semi-dry suit. This is not a watertight zipper. Semi-dry suits are effectively a wetsuit with improved seals at wrist, neck and ankles and also usually featuring a watertight zipper. Together these features greatly reduce the amount, of water moving through the suit as the wearer moves in the water. The wearer gets wet in a semi-dry suit but the water that enters is soon warmed up and is not "flushed" out by colder water entering from the outside environment, so the wearer remains warm longer. The trapped layer of water does not add significantly to the suit's insulating ability. Any residual water circulation past the seals still causes heat loss, but this loss is minimised due to the more effective seals. Though more expensive and more difficult to take on and off than a wetsuit (in most cases, a helper will be needed to close the dry-zip, which is usually located across the shoulders) semi-dry suits are cheaper and simpler than dry suits and in the case of scuba diving, require no additional skills to use. They are usually made from thick neoprene (typically 6 mm or more), which provides good thermal protection at shallow depth, but lose buoyancy and thermal protec,tion as the gas bubbles in the Neoprene compress at depth, like a normal wetsuit. Early suits marketed as "Semi-dry" suits came come in various configurations including a, one-piece full-body suit or two pieces, made of 'long johns' and a separate 'jacket'. Almost all modern semi-dry suits are one piece suits, with the zipper usually being across the shoulders on the back, but other arrangements have been used. Semi-dry suits do not usually incorporate boots, and most models do not include a hood, (as creating a good seal around the face is difficult) so a separate pair of wetsuit boots, hood and gloves are worn, as needed. They are most suitable for use where the water temperature is between .