Renting instead of buying new products may be seen as the most efficient strategies of the circular economy. However, changes in the consumption inevitably liberates or binds scarce production or consumption factors such as raw materials, money and time which can potentially limit the potential to save resources. This phenomenon is known as environmental rebound effect and is currently under-researched in the context of resource sharing. This paper reviews the magnitude and tendency of environmental rebound effects of peer-to-peer boat sharing platform using a double-spending model (i.e. for lessors as well lessees). We found that environmental rebound effect was experienced by every lessee surveyed (n = 104) and in one-third of lessors (n = 29). 60 % of lessees experienced a rebound of over 20 %, losing one-fifth of the potential reductions in emissions through subsequent consumption behaviour enabled by the economic savings created by sharing resources. International air travel and increases in personal use of the boat were the biggest contributing factors towards environmental rebound effect. Users that increased consumption in these ways experienced a backfire effect in which their annual emissions actually increased. This backfire was experienced by 29 % of lessees with the worst scenario increasing emissions by a factor of over eight. We found statistically significant differences in the rebound of lessors and lessees. Greater awareness and non-economic mechanisms (such as symbolic rewards, information provision and nudging) tailored for lessors and lessees are needed to help prevent the likelihood of occurrence and the magnitude of environmental rebound effects from sharing resources.