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  • Overview
  • Objectives
  • Skills you gain
  • Costs to Consider
  • Site Conditions

2024 Dates

2 weeks: 1 week terrestrial & 1 week marine – 1 August14 August 2024
2 weeks: 1 week terrestrial & 1 week marine – 15 August – 28 August 2024
4 weeks: 2 weeks terrestrial & 2 weeks marine – 1 August – 28 August 2024

Click Here for Expedition Dates

The Mediterranean biodiversity research is carried out in the valley of Krka National Park. At this site you will be working from dawn until late morning and then again in the late afternoon and evening helping a series of different research teams. During the heat of the midday period you will have a series of lectures about Balkans wildlife and conservation and help with data input and lab-work using samples sourced from the field. The projects include standardised transect surveys through a series of different habitats for butterflies (Pollard surveys), herpetofauna (standard search transects), birds (point counts), mammals (standard search transects for scat and tracks) and bats (acoustic surveys). In addition, there are standardised monitoring locations for bird and bat mist netting in a range of habitats and surveys to quantify the habitat at each of these standardised survey locations. On top of these standardised surveys designed to provide long-term data on the different faunal groups there are a series of investigations to describe population densities and ecology of groups such as grasshoppers, crickets, cave fauna (standard search transects and quadrats), nocturnal surveys of cat snakes (Telescopus fallax), Hermann’s tortoise (Testudo hermanni), Dalmation algyroides (Algyroides nigropunctatus) lizards and the effect of wolves on predator composition (camera trapping).

For the marine research experience you will be based on the beautiful and peaceful Silba Island. You will start with some training, beginning with the opportunity to complete a PADI Open Water dive training course if you would like to learn and are not already qualified, followed by a compulsory Mediterranean ecology and survey techniques course, with two lectures and two practicals each day (either by diving or snorkelling). After completing this training, those of you staying long enough will move on to assisting with some of the research surveys on Mediterranean fish communities, the recovery of the Noble Pen (Pinna nobilis) mollusc populations, the impact of sea urchin populations and the role of seagrass meadows in supporting fish and invertebrate biodiversity.

Croatia Terrestrial Research Objectives

Krka National Park

The Krka Valley runs from the Dinaric mountains bordering Bosnia to the Adriatic and is only 77km in length. However, since the river runs through limestone there are some spectacular gorges and this is one of the most scenic river valleys in Europe. It is also important from a biodiversity viewpoint containing nine Croatian and three Krka endemic fish species and spectacular cave systems containing a number of potentially new species to science. Opwall together with Biota (a Croatian biodiversity research organisation) has built a research centre in the central part of the Krka valley with easy access to the whole park. The centre is based in a restored house and grounds within 100m of the park boundary and has access to all the habitats throughout the park and surrounding countryside. The National Park Authority have requested we perform baseline surveys to increase the known inventory for the Park, as well as collect long-term monitoring data to answer a series of their management questions.

Tourist visits to Krka National Park are heavily concentrated towards the lower stretches of the river and very few people visit the central and northern parts of the valley. The Biota/Opwall research centre is based within a rural community that has suffered from significant depopulation and land abandonment in recent years. The centre is designed to give benefits to the local community from the visits (e.g. provision of employment etc). Whilst the main research effort each year from this centre comes through the Opwall programme, the centre will remain open year round in an attempt to attract some of the many visitors to the Croatian coast further inland, increasing revenue for the Park and local communities.

Croatia Marine Research Objectives

Silba Island

Silba Island is in the northern Dalmatian archipelago and is a car and hotel free island. The island markets itself as a haven of tranquillity and much of the island is still covered by Mediterranean black oak and maquis. The objective for our partners on this island is to develop the first marine research centre for northern Dalmatia and they have a series of research projects on seagrass, sea urchins, protected species and fisheries, as well as marine plastics.

  • Attend lectures/workshops on biodiversity and conservation
  • Learn about the biogeography of the Dinaric karst and mountains
  • Explore unique cave flora and fauna
  • Learn many different survey methods for freshwater fish, birds, snakes and mammals
  • PADI Open water dive qualification
  • Participate in Adriatic ecology course
  • Help in estimating the health of sea grass
  • Help in establishing No-take zones for fishing
  • Learn to estimate population of endemic and endangered Nobel shell
  • Learn to adapt to team work and experience its importance
  • Opwall fee.
  • Cost of international flights into and out of Split or Zadar.
  • Cost of internal travel to and from the start and end point of the expedition, plus any hotels you might require. The standard internal travel package costs around £277 or $305.
  • Extra nights’ accommodation in Split or Zadar costs £115 or $127 (breakfast included).
  • Park entrance fees – £46 or $50.
  • Dive equipment rental – £60 or $75 per week for a full dive kit. Or if you are planning on snorkeling, snorkel equipment hire is £35 or $45. Please note that wetsuits cannot be provided – you should bring your own.
  • PADI manual and PIC card (if you are completing your Open Water qualification) – £69 or $89 approx.
  • Vaccinations and prophylactic medicines – cost can vary depending on your healthcare provider.
  • All prices in GBP or USD unless specified.
  • ETIAS – please refer to our travel information for more detail.
  • Standard travel insurance – cost can vary, for 2 weeks it can range anywhere from £40-80 or $40-150.

Most of our volunteers fundraise for their expedition costs. Find out more.

Croatia is hot during this time of the year! In both Krka and Silba the daytime temperature rarely drops below 30 degrees and can reach 40 degrees.

Fitness level required
Moderate. Whilst there are not many steep hikes in the forest, the hikes are still quite long and the temperature can make them tiring.

Creature comforts
At Krka you will either be staying in dormitories or in shaded tents with shared western style bathrooms and toilets. In Silba it will be in dormitories, again with shared bathroom facilities. There is some limited phone signal in Krka (but not reliable for a data connection), but good phone signal in Silba.


  • Croatia
  • Silba
  • Krka National Park

Want to get involved with this project?


Want to get involved with this project?

Wallace House, Old Bolingbroke, Spilsby, Lincolnshire PE23 4EX, UK
| +44 (0) 1790 763194 | info@opwall.com