What is the advantage of a semi-dry suit compared to a dry suit?

A semi-dry suit is designed to offer thermal protection while allowing a small amount of water ingress. This feature allows the suit to keep the diver warm by creating a thin layer of water between the suit and the diver's skin, which can be warmed by body heat. The suit is typically constructed in a way that minimizes the amount of water that can enter, helping to maintain a comfortable temperature for the diver in cooler conditions.

The other options describe characteristics that are not accurate for a semi-dry suit. A semi-dry suit does not provide complete dryness, which is a hallmark of a fully dry suit. While a semi-dry suit can be lighter and thus easier to transport compared to some dry suits, the primary advantage lies in its thermal protection capabilities. It is also not specifically designed for use in warmer conditions but is intended for a range of temperatures, making it versatile for various diving environments.