From Collector's Weekly:
Seaweed collecting embodied a cross-section of Victorian-era pursuits, allowing people to explore nature, improve their scientific knowledge, and create an attractive memento to decorate their homes. By the 1840s, several books on identifying and preserving seaweed had been published...
Both men and women participated in these cultural trends, and there were definitely male seaweed collectors. In fact, Mary Carrington’s album contains a calling card for a man named W. H. Gould onto which has been placed beside a tiny seaweed specimen. But while male collectors were able to join the ranks of the professional scientists, women were largely restricted to domesticated versions of the same occupations. They were encouraged to collect seaweed not as a scientific undertaking but as a sentimental hobby and a social accomplishment.
Part of the appeal was what a seaweed collection said about the collector. Anyone could appreciate and collect flowers, but painstakingly obtaining, preserving, and mounting seaweed specimens demonstrated patience, artistic talent, and the refined sensibilities necessary to appreciate the more subtle beauties of nature. Queen Victoria herself made a seaweed album as a young lady.