Abstract: A spear gun is collapsible to approximately one-half of the full length of a conventional spear gun by the use of both (1) a spear made of two parts and (2) by the use of a hollow shortened spear gun housing from which an extension for holding the slings or elastics for propelling the spear may protrude. The extension is slidably mounted within the hollow spear gun housing and has at its outer end a sling holder, or arrangements for holding the slings or elastics. The spear has a threaded coupling halfway along its length so that the spear may be unthreaded and the two parts thereof both secured along the length of the housing. One of the parts may be stored on the gun when the gun is not in use. A special compact trigger mechanism may include a release shaft in the hand grip of the spear gun which interfits with a recess in the spear, and is provided with a thumb actuated release. Concurrently with releasing the spear, the other end of the shaft includes a mechanism which releases the spear retaining line.