My son wants a dive light for his bday. He was impressed with the Tusa 300. Any other recommendations?
My older daughter also had questions on a dive light. You should take a look at the generic LeisurePro website which has many dive lights, and also at the PrincetonTec and other mainline diving light websites.
Based on my previous experience with the PrincetonTec Torrent Xenon bulb version, my daughter settled the PrincetonTec Torrent with the Xenon bulb rather than the LED. The Xenon puts out 115 Lumens whereas the more expensive LED version puts out only 95 lumens. Notice that the light actually takes 8AA cells, 2x4AA in parallel, to increase the runtime, although you can use only 4xAA as well. Note that the earlier model of the same basic light received good comments on CPF as a general flashlight.
However, my recommendation was any of the dive lights with 3 LEDs using the 4 C cells. The 8C cell versions are rather large to provide long run time. Most hobby divers do not stay down that long. For the size, I would recommend the PrincetonTec Miniwave LED version. Ikelite, Pelican, Tektite all have competing products. The form factor is popular. Do be careful of sales on older versions with lower-power LEDs.
However, whatever you choose, if he is going diving where he _needs_ a light, do not allow him to go in to the water with only one light. He needs a bag light as backup. It can be really dark down there. Buddying up is obvious. Also, if the diver is not able to simply drift up, or even see light "up", that diver has a potential problem.