Pressure layer combines all human activities that cause physical disturbance or damage to seabed. For several human activity datasets, spatial extents were given (table below). Buffers with decreasing value rates were applied to represent the impact distance of physical disturbance. The following human activities were combined into the physical disturbance layer; - Cables (under construction, 1 km buffer) - Coastal defence and flood protection (under construction, 500 m buffer) - Deposit of dredged material (500 m buffer for points and areas) - Dredging (maintenance) (500 m buffer for points and areas) - Extraction of sand and gravel (500 m buffer) - Finfish mariculture (1 km buffer) - Fishing intensity 2011-2016 average (subsurface swept area ratio) - Furcellaria harvesting - Pipelines (0,3 km buffer) - Recreational boating and sports - Shellfish mariculture - Shipping density - Wind farms (under construction) (1 km buffer) - Wind farms (operational) (0,1 km buffer) The human activity data sets were first processed separately covering the whole Baltic Sea and then summed together. In this integration, some data layers were down-weighted to arrive at a balanced pressure layer, as described below. High pressure intensity and/or slow recovery (weighting factor 1): Coastal defence and flood protection, Deposit of dredged material, Dredging, Extraction of sand and gravel and Fishing intensity Moderate to high (Weighting factor 0,8): Pipelines and Shipping density Moderate (Weighting factor 0,6): Finfish mariculture, Shellfish mariculture and Wind farms (under construction) Low to moderate (Weighting factor 0,4): Cables Low (Weighting factor 0,2): Maerl and Furcellaria harvesting, Recreational boating and sports and Wind farms (operational) Harbours and marinas were left out from the physical disturbance pressure to avoid double counting due to their representation in the shipping density and recreational boating and sports data sets. Detailed information about this pressure layer can be found in the indicator report.

This dataset contains core indicator results developed under the HELCOM Third Holistic Assessment of the Ecosystem Health of the Baltic Sea (HOLAS 3).

This dataset contains ferrybox data reported by HELCOM Contracting Parties and used for Chlorophyll-a indicator in the HELCOM Third Holistic Assessment of the Ecosystem Health of the Baltic Sea (HOLAS 3). The Ferrybox data consists of on-board measurements taken on commercial ship routes and collated by Finnish Environment Institute SYKE. Data has been reported to ICES using the ICES Oceanographic data format for PUMP data type. https://www.ices.dk/data/data-portals/Pages/ocean-format.aspx https://www.ices.dk/data/Documents/ocean/ICES-Oceanography-Data-Submission-Format.zip Attribute description (ODV format): Cruise: Cruise label to identify the given cruise Station: Station label to identity the given station yyyy-mm-ddThh:mm:ss.sss: Date and time of the given station (year, month, day, hour, minute and seconds) in UTC Latitude [degrees north]: Latitude in decimal degrees in WGS84 Longitude [degrees south]: Longitude in decimal degrees in WGS84 Bot. Depth [m]: Bottom Depth in metres Depth [m]: Depth [m] of the given sample QV:ODV:Depth [m]: Quality Flag of the given Quality Flag Scheme and variable Temperature [degC]: Temperature in degree Celsius of the given sample QV:ODV:Temperature [degC]: Quality Flag of the given Quality Flag Scheme and variable Practical Salinity [dmnless]: Practical Salinity of the given sample QV:ODV:Practical Salinity [dmnless]: Quality Flag of the given Quality Flag Scheme and variable Dissolved Oxygen [ml/l]: Dissolved Oxygen in ml/l of the given sample QV:ODV:Dissolved Oxygen [ml/l]: Quality Flag of the given Quality Flag Scheme and variable

This dataset contains monitoring data reported by Contracting Parties of HELCOM to ICES DOME database and extracted for use in Hazardous substances indicators under the HELCOM Third Holistic Assessment of the Ecosystem Health of the Baltic Sea (HOLAS 3). Attribute specifications and units: series region l3area: HELCOM ID for HELCOM assessment units in scale 3 l4area: HELCOM ID for HELCOM assessment units in scale 4 country station_co: station code station_na: station name station_lo: station long name latitude: latitude longitude: longitude MSTAT WLYTP determinan: determinand determin_1: determinand group species matrix basis unit sex metoa series_typ: series type sym_shape colour n_year_all n_year_fit n_year_pos: n year positive first_year: first year all first_ye_1: first year fit last_year p_nonlinea p_linear p_overall p_linear_t: p linear trend linear_tre: linear trend p_recent_t: p recent trend recent_tre: recent trend detectable: detectable trend mean_last_: mean last year climit_las: climit last year BAC_type BAC_value BAC_diff BAC_achiev BAC_below EAC_type EAC_value EAC_diff EAC_achiev EAC_below imposex_cl: imposed class

This dataset represents the underlying data on the pre-core indicator Diatom/Dinoflagellate index for HOLAS 3. The core indicator evaluates phytoplankton community structure to determine whether it reflects good environmental status. Quantitative thresholds are used to evaluate if core indicators status is Good, Not good or Not assessed.

This dataset contains data used for the HELCOM Core indicator State of the soft-bottom macrofauna community for HOLAS 3. Attribute information: "SampleID" = Sample ID "Station" = Station name "Year" = Year of sampling event "Latitude" = Latitude coordinate (WGS84 decimal degrees) "Longitude" = Longitude coordinate (WGS84 decimal degrees) "Depth" = Depth of station (m) "Sentivit" = Sensitivity subset "Sampling_a" = Sampling area (cm2) "Sieve_mesh" = Sive mesh size (microm) "BQI" = Benthic quality index value "Data sourc" = Source of data (national monitoring / other) "Data_origi" = Data providing organization "Country" = Data providing country "Assessment" = HELCOM Level 2 assessment unit where the station resides

The Baltic Sea Pressure index (BSPI) assesses the potential cumulative pressures in the Baltic Sea. The BSPI is based on georeferenced datasets of human activities (28 datasets), pressures (17 datasets) and uses the average sensitivity of each pressure layer to all ecosystems to weigth the pressure. Cumulative pressures are calculated for each assessment unit (1 km2 grid cells) and the data set covers the time period 2016-2021. Spatial Pressure and Impact Assessment (SPIA) is the framework for assessing spatial and cumulative pressures and impacts in HOLAS 3, where the BSPI presents the full cumulative pressure assessment where all pressures are included. The framework also includes results for the Baltic Sea Impact Index (full cumulative impact assessment), and other thematic assessments where a subset of pressure and ecosystem layers are used. For more info please - visit the HOLAS 3 website (http://stateofthebalticsea.helcom.fi/) - download the report thematic assessment of spatial distribution of pressures and impacts 2016-2021 (https://helcom.fi/post_type_publ/holas3_spa) - or check out the HELCOM SPIA online tool to make calculations for any desired combination of pressures and ecosystem layers (https://maps.helcom.fi/website/bsii/). Please scroll down to "Lineage" for a more detailed description of the methodology.

This core indicator evaluates the status of coastal sea areas of the Baltic Sea based on the abundance of sea trout parr in rivers where they breed. The determination of whether good status is reached is based on a comparison of the observed parr densities in rearing habitats with the reference potential parr densities in the specified habitats. This dataset displays the result of the indicator in HELCOM Assessment Scale 3 (Division of the Baltic Sea into 17 sub-basins and further division into coastal and offshore areas). Attribute information: "HELCOM_ID" = ID of the HELCOM scale 3 assessment unit "level_2" = Name of the HELCOM scale 2 assessment unit "level_3" = Name of HELCOM scale 3 assessment unit "ICES Subdivision" = ICES assessment unit number "Area (km2)" = Area of the HELCOM scale 3 assessment unit "Indicator_" = Name of the indicator "Unit" = Unit of the indicator "Type" = 1 = boundary values increase/decrease monotonically, 2 = optimum range indicator "Status" = Status of the indicator (“Achieve”, “Fail” or “Not assessed”) "ConfA" = Confidence of classification "ConfT" = Temporal confidence of classification "ConfS" = Spatial confidence of classification "ConfM" = Methodological confidence of classification "notes" = additional info "AULEVEL" = Assessment unit level used for the indicator

This dataset contains points of information describing the location and size of spills of mineral oil observed during aerial surveillance flights by HELCOM Contracting Parties during 1998-2023. The data covers detections from fixed-wing aircraft only. Since 2014 Contracting Parties have also reported spills of other substances and unknown substances. The purpose of the regional aerial surveillance is to detect spills of oil and other harmful substances and thus prevent violations of the existing regulations on prevention of pollution from ships. Such illegal spills are a form of pollution which threatens the marine environment of the Baltic Sea area. Further information on detected spills in the Baltic Sea area and HELCOM aerial surveillance activities can be found at http://www.helcom.fi/baltic-sea-trends/maritime/illegal-spills/ and https://helcom.fi/action-areas/response-to-spills/aerial-surveillance/ The dataset contains the following information: Country Year Spill_ID = A unique code which will enable each individual spill to be individually identified FlightType = The type of flight the detection was made during: National = "N", CEPCO = "C", Super CEPCO = "SC", Tour d’Horizon = “TDH” Date = The date of the detection (dd.mm.yyyy) Time_UTC = The time of the detection in UTC (hh:mm) Wind_speed = The wind speed at the time of the detection (m/s) Wind_direc = The wind direction in degrees at the time of the detection (degrees) Latitude = The latitude of the detection (decimal degrees, WGS84) Longitude = The longitude of the detection (decimal degrees, WGS84) Length__km = The length of the detection (km) Width__km = The width of the detection (km) Area__km2_ = The area of the detection (km2) Spill_cat = Spill/pollution category: Mineral Oil = “Oil", Other Substance = "Other substance" , "Unknown substance" = “Unknown” EstimVol_m = If Spill_cat="Oil", then estimated min. volume of oil spill. Volume of the detection confirmed/observed as mineral oil as calculated using the Bonn Agreement Oil Appearance Code using the lower figure (BAOAC minimum) in m3. Vol_Category = Category of the detection: <0,1m3 = “1”, <0,1-1m3 = “2”, 1-10 m3 = “3”, 10-100 m3 = “4”, >100 m3 = “5” Type_substance = If Spill_cat="Other substance" or "Unknown. Product name or type of OS or GAR substances that could be identified (in case of known polluter, or via visual identification - cf. BAOAC Atlas). - Examples for OS: vegetable oils (palm oil sun flower oil, soya oil etc.), fish oil, molasses, various chemicals (methanol, biodiesels/FAME, toluene, paraffines etc.); Examples of GAR: solid cargo residues (e.g. coal residues), plastics, fish nets, … OR "Unknown" (in case the type of substance could not be identified) Polluter = Type of polluter source: Offshore Installation = “Rig”, Vessel = “Ship”, Other Polluter or source (e.g. land based source) = “Other”, Unknown = “Unknwon” (in case of an “orphan” spill that cannot be linked to a polluter) Remarks = Any additional information to inform on particular situations Description of marine litter sightings

This core indicator evaluates the status of the marine environment based on concentrations of perfluorooctane sulphonate (PFOS) in water. Quantitative thresholds are used to evaluate if core indicators status is "Achieve", "Fail" or "Not assessed". Good status is achieved when the concentrations of PFOS are below the threshold value. This dataset displays the result of the indicator in HELCOM Assessment Scale 4 (Division of the Baltic Sea into 17 sub-basins and further division into coastal and off-shore areas and division of the coastal areas by WFD water types or water bodies). Attribute specifications and units: "HELCOM_ID" = Code of the HELCOM scale 4 assessment unit "country": country in which the HELCOM assessment unit is located or a mention to an open sea area "level_2" = Name of the HELCOM assessment unit in scale 2 "Name" = Name of the HELCOM assessment unit in scale 4 "Open_sea" = Name of the HELCOM assessment unit in the open sea "F2_Name" = Name of the HELCOM assessment unit "determinan" = Determinat "est" = The estimated mean loge concentration in the assessment unit "se" = The standard error on the estimated mean log concentration in the assessment unit "fit" = The estimated mean concentration in the assessment unit "upper_cl" = Upper one-sided 95% confidence limit on the mean concentration: exp(est + qnorm(0.95) * see) "Status" = Overall Status of the indicator according to one-out-all-out