Tsunami deposits can provide useful information on the palaeotsunami history of a coastal region, extending far beyond the range which is covered by historical records. The main issue when studying tsunami deposits is their differentiation from storm surge deposits, which are often similar in appearance. Field survey was carried out in Thailand (Khao Lak, Tsunami 2004) and the Dominican Republic, followed by detailed sediment-petrographical and ecological analyses. Masses of large boulders and the hydraulic conditions for their transportation have been calculated and discussed. In the area of Khao Lak, the prevalent tsunami deposits are silty-sandy sediment layers. Generally, these sediments differ significantly from pre-tsunami sediments and soils due to their higher silt, clay and carbonate content. However, these differences decrease towards estuarine channels and mouths. Distant to estuaries, the tsunami deposits also show a significant difference to recent beach sands. On the basis of petrographic characteristics, fine-grained, sub-wave base shelf sediments have been identified as a major source for the tsunami deposits. In addition to these sediment layers, a local deposition of coral boulders by the tsunami has also been observed In the Dominican Republic, wave-deposited sediments have been detected in various coastal areas (sandy sediment layers: NE and SW coast; boulder deposits: south coast), representing the first investigation of tsunami and storm deposits on the island of Hispaniola. A massive, fine-grained carbonate sand layer, overlying carbonate-free silty clay in depths of 20-38 cm, was observed in the area of Playa Cosón (NE-coast). The topographic position of the sand layer (220-260 m landward of the present shore and landward of a 2 m high, sandy ridge) and the presence of a syn-sedimentary, landward-directed flame structure favours the interpretation of a deposition by a tsunami. Due to its stratigraphic position, the sand layer is interpreted as deposited by the 8th of August, 1946 tsunami event. The foraminiferal assemblage is dominated by taxa, which typically occur in tropical, shallow marine areas. However, a very small amount of foraminifers from outer shelf to bathyal depths is also present. In the SW, a bioclast-rich sand layer, overlying carbonatic silty clay in depths of 30-83 cm, was detected at Puerto Viejo. A clear decision whether a tsunami or a storm was responsible for the deposition of this sand layer was not possible on the basis of topographical (up to 160 m landward of the present shore, 1 m above mean sea level), sedimentological and sediment-petrographical characteristics, the latter often being influenced by bioturbation. Relatively high amounts of planktonic foraminifers, together with single occurrences of radiolarians were observed in the sand layer. The benthic foraminiferal assemblage is dominated by shallow marine taxa, but a small amount of deeper shelf and bathyal forms is also present. Consequently, this sand layer can be interpreted as deposited by a tsunami (October 1751 event), as storm waves are not able to transport sediments from such depths onshore. Wave-deposited boulders were observed along the southern coast east of Santo Domingo, which is formed by an elevated carbonate platform of Pleistocene age. Except for rarely-occurring young coral boulders, all boulders originated from the seaward edge of the platform. The boulders mostly occur as single boulders (accumulations, including ridges and ramparts are rare) in distances of several tens of metres to the shore and several metres above mean sea level. 18 boulders show masses > 25 t, with the largest having a mass of about 90 t. Some boulders clearly show characteristics for a deposition by a tsunami, whilst others can clearly be interpreted as storm deposits. In summary, these boulders are interpreted as deposited by at least one prehisto