The rapidly growing whale watching industry and increases in ambient underwater noise has raised concerns regarding the possible effects of this type of ecotourism on marine mammals. During the months of January-March 2008, three simultaneous studies were conducted on; 1) the effects of engine noise of gray whales; 2) possible effects of the presence of one or more whale watching vessels on gray whale behaviour and; 3) to investigate the expectations and perceptions of whale watching tourists in Bahia Magdalena, Baja California Sur, Mexico. A variety of methodologies were utilized, such as underwater acoustic noise measurements of two outboard engine types (two stroke and four stroke) used by whale watching boats, behavioural observations (respiration rate) of gray whales in the presence of one or more whale watching vessels and questionnaire survey sampling of whale watching tourists visiting Puerto San Carlos, a fishing village located around Bahia Magdalena. Ambient noise in the bay ranged between 112-131 SPL (dBRMS re 1μPa). The four stoke engine produced louder SPL values than the two stroke engine, 109-136 dB RMS re 1μPa and 103-140 dB RMS re 1μPa respectively. The mean respiration rate per minute was 1.06, for adult whales, 0.62 for females with calves and 1.38 for calves. Respiration rates of individual adult whales, mother with calves and calves were not affected by the presence of one or more whale watching vessels. The ambient noise I the bay also appears to have no effect on the behaviour of gray whales. Over 100 questionnaires were distributed to whale watching tourist visiting Puerto San Carlos. Naturally tourists expected to see whales during their tour but only a few expected to touch or get extremely close to whales. Tours were generally highly rated and touching a whale was perceived as an additional bonus by tourist. Several avenues to improve tourist satisfaction were identified, such as providing more information about gray whale and the history of the bay and providing refreshments (food and beverages). The data collected from this study can be used to enhance existing whale watching regulations for gray whale conservation and ecotourism management in Bahia Magdalena.