How large our Marine Forests are at present? The distribution of subtidal kelp forests in northern Portugal was surveyed more than a decade ago and covered an area of less than 150 km2. We are currently monitoring subtidal kelps’ distribution using innovative techniques to determine how large our marine forests are and then studying their impact on coastal ecosystem functioning and associated ecosystem services. Currently, we have surveyed more than 250 km2 and found that their distribution is larger than originally suspected.