As human impact on marine ecosystems continues to grow, so too does the need for sound conservation and management strategies that are informed by science. Cetaceans, the whales, dolphins and porpoises, epitomise this challenge, because they are hard to study, they have been heavily exploited in the past, and because some of their habitats, behaviours and life-history strategies make them acutely vulnerable to human activities. Unfortunately, research on free-ranging cetaceans in remote areas is costly, and financial resources are limited. The approach used in this thesis to acquire inexpensive quantitative information on cetacean populations and behaviour was to seek out platforms of opportunity. Tourism and environmental education projects provided access to remote areas of importance to cetaceans. The topic was explored in two main areas. First, studies were conducted to investigate the use of ships of opportunity in estimating distribution and abundance, namely of Antarctic baleen whales. The second area of interest was the effect of boats on killer whales in the northeast Pacific. Platforms of opportunity proved valuable for collecting data to model the role of measurement error on abundance estimation. Measurement error was found to be a potential source of bias in four distance estimation experiments. Platforms of opportunity could be used to train observers on protocols, and to learn to use range- finding photogrammetric equipment well before conducting dedicated surveys, which would eliminate this source of bias, as well as estimating abundance in some cases. Abundance and distribution of three whale species were modelled using data collected aboard Antarctic tourist ships. Spatial modelling techniques were used to model distribution of minke, fin and humpback whales using line-transect data collected from a survey that could not be randomised. Strong gradients in animal density were predicted, which could be used to inform future surveys. In the meantime, rough estimates of abundance were obtained, and this approach shows promise for other areas where lack of resources makes systematic surveys prohibitively expensive. A government-funded environmental education project provided logistical support for two studies that dealt with effects of boats on killer whale behaviour. One quantified the extent to which a particular style of whalewatching was disruptive to whale behaviour, and commercial whalewatchers agreed to halt this activity. The other found that a protected area conferred benefit to killer whales, even though it protects only a fraction of the whales' habitat for a fraction of the year. The thesis contains four case studies that illustrate how inexpensive methods may be used to obtain practical quantitative information to aid decision-making about conservation and management of wild cetaceans that interact with (i.e., whalewatching), compete with (i.e., fishing) or are exploited by (i.e., whaling) humans.