Sign inSign up free Sign inSign up free Sign inSign up freeSalt water depth chart
Today's read
Recent public catches load as you reach this section.
7,086-acre Lough Swilly. Middle saltwater fishing map with official INFOMAR survey bathymetry, measured-cell fishing spots, official fish evidence, seasonal forage guidance, access context and current-rule links. The middle trip-scale survey reach of Lough Swilly, retaining only official survey-backed seabed cells that pass the Ireland release gates. The water tops out around 66 ft. The depth chart comes from INFOMAR (Geological Survey Ireland and Marine Institute) bathymetric survey data, so the contours are survey-derived rather than computer-modeled. The rest of this page walks each species through its year, using the map's own scoring.
The drawn water covers 7,089 acres wrapped in 42.7 miles of bank, broken up by an island. The 3.6 development index tells the story — a convoluted bank whose fishable edge far outruns the acreage. About 30% of the surface sits shallower than 15 ft — that's the weed-and-bait zone. Figure 10.8 mi of water from one end to the other, 3.8 mi at the beam. If the bite dies, Mulroy Bay - Inner is 3 mi to the southwest.
Marine Institute spawning, nursery, observation and range layers support the principal surveyed pelagic and groundfish. IFI's national and regional sea-angling publications support additional habitat-compatible recreational targets. This is occurrence and search guidance, not equal abundance, a section-level population estimate or a promised catch. The roster may combine exact-water monitoring with habitat-filtered official regional evidence; it does not imply that every species is equally abundant throughout the mapped section.
| Species | Evidence basis | Count / date |
|---|---|---|
| Bass (European Seabass) | official species listing | — |
| Mackerel (Atlantic Mackerel) | official species listing | — |
| Herring (Atlantic Herring) | official species listing | — |
| Whiting (Whiting) | official species listing | — |
| Flounder (European Flounder) | official species listing | — |
| Plaice (European Plaice) | official species listing | — |
| Sole (Common Sole) | official species listing | — |
| Thornback ray (Thornback Ray) | official species listing | — |
| Thick-lipped grey mullet (Thick-lipped Grey Mullet) | official species listing | — |
| Garfish (Garfish) | official species listing | — |
| Sea trout (Sea Trout) | official species listing | — |
Official species-evidence source.
When the water first warms, european seabass slide up into 3 to 25 ft. Summer is a 2 to 30 ft game here, winter a 10 to 55 ft one. Start at INFOMAR measured current seam. It's a current seam holding about 30 ft of water and rates prime come summer. The feeding windows run early morning and the evening. Keep a surface lure or a paddle-tail soft plastic rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 25 ft | dawn & dusk | Shoreline point (18 ft) | Paddle-tail soft plastic, Shallow minnow plug |
| Summer | 2 to 30 ft | dawn & dusk | INFOMAR measured current seam (30 ft) | Surface lure, Paddle-tail soft plastic |
| Fall | 4 to 40 ft | dawn & dusk | INFOMAR measured current seam (30 ft) | Slim metal lure, Minnow plug |
| Winter | 10 to 55 ft | midday | INFOMAR measured channel edge (36 ft) | Slow soft-plastic shad, Suspending minnow |
The spring pattern is a shallow one: atlantic mackerel in 5 to 45 ft. Midsummer fish sit out in 12 to 66 ft before dropping to 17 to 66 ft for winter. The spot to know is Deepest basin, a deep basin in about 65 ft of water that rates prime for atlantic mackerel in summer. Plan around early morning and the evening in the warm months. Summer baits: a feather rig or a small vertical jig gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 5 to 45 ft | dawn & dusk | INFOMAR measured current seam (30 ft) | Mackerel feather rig, Small silver jig |
| Summer | 12 to 66 ft | dawn & dusk | Deepest basin (65 ft) | Feather rig, Small vertical jig |
| Fall | 10 to 65 ft | dawn & dusk | INFOMAR measured current seam (30 ft) | Compact silver jig, Sparse feather rig |
| Winter | 17 to 66 ft | midday | Deepest basin (65 ft) | Small deep jig |
When the water first warms, atlantic herring slide up into 5 to 25 ft. Summer is a 15 to 50 ft game here, winter a 20 to 60 ft one. Start at Deepest basin. It's a deep basin holding about 65 ft of water and rates good come winter. The feeding windows run early morning and the evening. Keep a herring feather rig or a small silver jig rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 5 to 25 ft | dawn & dusk | INFOMAR measured shoal (15 ft) | Small herring feather rig, Micro jig rig |
| Summer | 15 to 50 ft | dawn & dusk | INFOMAR measured current seam (30 ft) | Herring feather rig, Small silver jig |
| Fall | 10 to 40 ft | dawn & dusk | INFOMAR measured current seam (30 ft) | Small feather rig, Compact silver spoon |
| Winter | 20 to 60 ft | midday | Deepest basin (65 ft) | Small silver jig, Sparse feather rig |
Early season whiting use the shallows, holding in 15 to 55 ft. Summer is a 19 to 66 ft game here, winter a 14 to 66 ft one. The chart's best answer is INFOMAR measured channel edge — channel edge, 36 ft, prime for spring. Best bite is early morning. Tie on a small vertical jig and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 15 to 55 ft | dawn & dusk | INFOMAR measured channel edge (36 ft) | Small silver jig, Two-hook feather rig |
| Summer | 19 to 66 ft | dawn | Deepest basin (65 ft) | Small vertical jig |
| Fall | 10 to 60 ft | dusk | INFOMAR measured channel edge (36 ft) | Small silver jig, Sparse feather rig |
| Winter | 14 to 66 ft | dusk | Deepest basin (65 ft) | Compact vertical jig |
The spring pattern is a shallow one: european flounder in 5 to 25 ft. Midsummer fish sit out in 6 to 35 ft before dropping to 15 to 50 ft for winter. The spot to know is INFOMAR measured flat, a feeding flat in about 8 ft of water that rates prime for european flounder in spring. Plan around early morning and the evening in the warm months. Summer baits: a bottom jig with spinner blade gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 5 to 25 ft | dusk | INFOMAR measured flat (8 ft) | Small bucktail dragged on bottom |
| Summer | 6 to 35 ft | dawn & dusk | INFOMAR measured flat (8 ft) | Bottom jig with spinner blade |
| Fall | 8 to 40 ft | dusk | Sharp break (8 ft) | Compact bottom jig |
| Winter | 15 to 50 ft | midday | INFOMAR measured channel edge (36 ft) | Small bottom jig |
Early season european plaice use the shallows, holding in 8 to 35 ft. Summer is a 6 to 40 ft game here, winter a 20 to 66 ft one. The chart's best answer is INFOMAR measured flat — feeding flat, 8 ft, prime for spring. Best bite is early morning and the evening. Tie on a light spooned bottom rig or a beaded trace and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 8 to 35 ft | dusk | INFOMAR measured flat (8 ft) | Beaded flowing trace |
| Summer | 6 to 40 ft | dawn & dusk | INFOMAR measured flat (8 ft) | Light spooned bottom rig, Beaded trace |
| Fall | 10 to 50 ft | dusk | INFOMAR measured channel edge (36 ft) | Beaded bottom trace |
| Winter | 20 to 66 ft | midday | Deepest basin (65 ft) |
Lough Swilly - Middle also holds common sole (3 to 30 ft in summer), thornback ray (10 to 65 ft in summer), thick-lipped grey mullet (1 to 18 ft in summer), garfish (2 to 20 ft in summer), sea trout (15 to 50 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Structure-wise the chart holds 7 features, led in depth by Deepest basin at roughly 65 ft.
Access data: Marine Institute — Fishing Ports. Confirm conditions and fees locally before you launch.
Season dates, license requirements, and size and bag limits for Ireland waters are set by the Inland Fisheries Ireland (current sea-angling regulations) — and special regulations can apply to Lough Swilly - Middle specifically, so confirm the current rules before you fish. Check the current national and water-specific rules before every trip, including bass measures, the 2026 recreational pollack controls, salmon and sea-trout licences and river-specific status, protected areas, harbour directions, private land and local signs. A mapped fishing port or measured seabed feature is not permission to fish, park, launch or enter a working harbour.
Check the official Ireland fishing regulations →
Department of Climate, Energy and the Environment (2026 salmon and sea-trout status) →
Check special-area and water-specific rules →
Check official shore-access information →
Lough Swilly - Middle is about 66 ft (20 m) deep at its deepest point. The depth chart comes from INFOMAR (Geological Survey Ireland and Marine Institute) bathymetric survey data, so the contours are survey-derived rather than computer-modeled.
Official coastal monitoring from Marine Institute and Inland Fisheries Ireland informs the european seabass, atlantic mackerel, atlantic herring, whiting, european flounder, european plaice, common sole, thornback ray, thick-lipped grey mullet, garfish, sea trout roster for Lough Swilly - Middle. The mixed roster combines exact-water records where available with habitat-filtered regional evidence; not every species is documented at this exact water, and it is not a promise of equal abundance or a catch on a particular trip.
INFOMAR measured current seam is the top-rated area: a current seam in about 30 ft of water that rates prime for european seabass in summer. Open the map above to see every rated spot for each species and season.
For european seabass, the summer bite is best in early morning and the evening. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Fishing on Lough Swilly - Middle is regulated by the Inland Fisheries Ireland (current sea-angling regulations). Check the official Ireland regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.
Mulroy Bay - Inner 3 mi · Lough Foyle - Inner 4 mi, IRL/UK · Mulroy Bay - Outer 10 mi · Lough Foyle - Middle 13 mi, IRL/UK · Lough Swilly - Outer 14 mi · Lough Foyle - Outer 19 mi, IRL/UK · Sheephaven Bay - East 20 mi · Sheephaven Bay - West 35 mi · The Rosses and Gweedore Bay - Outer Islands 42 mi · Gweebarra Bay - Outer 46 mi · Donegal Bay - Central East 49 mi · Donegal Bay - Central West North 51 mi
See how Lough Swilly - Middle stacks up: best sea trout lakes in Ireland · best atlantic herring lakes in Ireland · best european flounder lakes in Ireland · best garfish lakes in Ireland
Browse all Ireland fishing maps. See every water on DepthScout. Bathymetry credit: INFOMAR (Geological Survey Ireland and Marine Institute) INFOMAR All Survey bathymetry mosaic (Source-survey vertical references retained in the INFOMAR All Survey mosaic; 100% measured, 0% source-interpolated). How we build these maps. Fish here with a sonar unit that logs? Send us your depth data and we'll improve this chart, credited to you. For fishing guidance only, never navigation.