On basis of case histories of subsea tunnels and subwater tunnels in China and foreign countries, the author makes some comments on subsea tunnels in respect of engineering preparations, technical methods, option selection, risk management and engineering concept. The author states that for subsea tunnel works, future issues should be properly considered and early preparations and watertight arrangement should be made so as to avoid detouring course and not to lose any opportunity. After analyzing the advantages/disadvantages of some popular construction methods for subsea tunnels, such as immersed tube method, drill and blast method and TBM (Tunnel Boring Machine) method, the author makes some suggestions on the selection of the proper construction methods for subsea tunnels and provides some topics to which special attention should be paid and/or researches should be made. The author also makes some advices on the option selection of subsea tunnels in terms of location and alignment, tube