Physical and mechanical properties of gas-free aquatic muds control methane bubble descriptors such as size, shape, and orientation. These properties were quantified in Lake Kinneret using four gravity cores (A–D) collected along a northwestern transect at water depths of 27.5–38 m. Undrained shear strength was measured using a Torvane and estimated empirically; both approaches show a consistent increase with depth, reaching maximum values of 1.8 kPa at 1.55 m (A), 1.6 kPa at 1.75 m (B), 4.7 kPa at 2.33 m (C), and 2.7 kPa at 2.15 m (D). The suspension–sediment interface is identified by sharp density transitions at ρ = 1.28 g cm⁻³ (0.675 m, A), 1.27 g cm⁻³ (0.775 m, B), 1.20 g cm⁻³ (0.625 m, C), and 1.11 g cm⁻³ (0.525 m, D). Water content decreases with depth from 329–122% (A), 311–109% (B), 372–112% (C), and 461–116% (D), accompanied by porosity reductions from ~90% near the sediment surface to ~76% in cores A and B, to ~70–75% in cores C and D. Atterberg limits are nearly depth-invariant, with LL ≈ 67% and PL ≈ 37% in cores A and B, and LL ≈ 75%, PL ≈ 32%, and PI ≈ 43 in cores C and D, consistent with high-plasticity silty clays. Ultrasonic P-wave velocities in intact cores are irregular (~500–1490 m s⁻¹), attributed to internal cracks and voids, whereas remolded muds show a monotonic increase with depth (1462–1492 m s⁻¹). Mode I fracture toughness, estimated from porosity data, ranges between 53–89 Pa·m¹ᐟ² across the cores, yielding predicted methane bubble heights of 1.6–2.4 cm (A1, A2) and 2.0–2.6 cm (NW1, NW2). These results demonstrate that basic geotechnical indices provide a robust framework for predicting elastic and fracture properties of aquatic muds, improving methane bubble parameterization.