Measuring wall thickness underwater is a challenge. There are two options for taking measurements;

50 Foot Underwater Probe / Cable Assembly

1. Use a standard gauge with long underwater probe. This method requires 2 people, one on land with the instrument and a diver with a communication device. For this method we offer a 50 ft under water probe -> https://www.checkline.com/product/TI-25-UW-50

Underwater Ultrasonic Thickness Gauge

2. Use of an underwater ultrasonic thickness gauge. This method only requires 1 person, a diver with a waterproof, submersible thickness gauge. For this application we offer our TI-UMX2 -> https://www.checkline.com/product/TI-UMX2