Gylvira

The gylvira is a kind of yellow algae with green stems. The maceration that we get from it allows to breathe much longer under water. It is sold in one pint flask which are equivalent to 5 doses. Note that the gylvira gives very bad breath for the next hour.
For a swallowed dose of gylvira, the subject can breathe underwater for 1 minute longer than his constitution allows. As a reminder, a creature can normally breathe underwater for a number of minutes equal to 1 + its Constitution modifier. The organism is saturated after 10 doses and the duration of breathing under water no longer increases after that. The gylvira works only underwater and has no effect if the subject cannot breathe for any other reason.