On 21 September, Åland Post will issue a stamp that draws attention to some of the Baltic Sea’s most important yet least visible organisms: microalgae. The issue is based on photographs by Finnish hydrobiologist Tore Lindholm, who has studied microalgae in Åland waters for more than 50 years.
“This stamp issue highlights a world that is rarely seen, yet is vital to both the Baltic Sea ecosystem and life on our planet. Science and art meet in a motif from the sea that surrounds Åland. On the stamp, the microalgae appear as nature’s own works of art”, says Johanna Finne, Design Manager at Åland Post Stamps.
Microalgae are the oceans’ most important primary producers and form the foundation of marine food chains.
“Microalgae are found everywhere: in seas and lakes, on coastal rocks, stones and sand, and on aquatic plants. Free-floating algae are called phytoplankton, and they produce nearly half of the Earth’s oxygen. They display remarkable diversity in shape and colour. Their movements are fascinating too: ultra-fast jumps, rotations and gliding movements. The Baltic Sea is home to several thousand species, even more are found in freshwater environments,” says Tore Lindholm, who has studied algae in the Baltic Sea since the 1970s.
The stamp features the diatom Chaetoceros wighamii, photographed in material found in the inlet of Inre Verkviken, Saltvik, Åland. It forms chains of cells and long bristles, which reduce sinking and grazing by zooplankton. The stamp sheet includes additional microalgae, revealing the great variety of forms and structures hidden beneath the water.
The photographs used for the stamp issue were taken using an inverted microscope with phase-contrast optics. This technique enhances contours and makes it possible to see organisms that are often only a few hundred micrometres long.
Name of issue: Microalgae
Date of issue: 21 September 2026
Photographer: Tore Lindholm
Design: Johanna Finne
Edition: 30,000
Denomination: Världen (€4.70)
Stamp size: 40 × 30 mm
Sheet size: 185 × 264 mm
Stamps/sheet: 2 × 12
Paper: 110 g/m²
Perforation: 12 per 2 cm
Process: 4-colour offset
Printer: Gutenberg AG
Order the stamp and first day cover from the webshop.