SINGAPORE - More slots have been opened up to those who would like to visit Singapore's first marine park at Sisters' Islands. The first two guided trips at low tide in August, expanded to take 45 people up from the original 15, are already full. Such walks can be held only when there are suitably low tides.

The National Parks Board on Tuesday released dates for six more walks between September and December. These will each take up to 45 people and be opened for public registration in phases at www.nparks.gov.sg/sistersislandsmarinepark.

NParks will strike a balance between conservation and visitorship, said Minister of State for National Development Desmond Lee, such as by installing stepping-stones or boardwalks to give public access while protecting delicate intertidal areas.

He was speaking on the sidelines of a guided visit on Tuesday to the lagoon on the bigger of the pair that make up Sisters' Islands.

National Biodiversity Centre deputy director Karenne Tun said the numbers for guided walks were similar to those at other areas like Chek Jawa.

NParks will also do studies to work out how many people currently visit, how many the area can handle, and which areas are safest to walk in, she added.

The establishment of the 40-hectare Sisters' Islands Marine Park, which includes the western reefs of St John's Island and nearby Pulau Tekukor, was announced on Saturday at a biodiversity outreach fair at Vivocity.

Mr Lee also did a symbolic hand-over of a lab-grown giant clam to Dr Neo Mei Lin, 28, a research fellow at the Tropical Marine Science Institute, who planted it underwater off Big Sister's Island.

Reintroduction of the giant clams, endangered in Singapore, is one of the research projects planned at the new park.