“(the) Wonder/miracle two/second is/: the mouth/estuary/ostium of the river/stream/fluminus transhannon(i)/Trahannon(i)/thrannoni /strannoni /Tranon/Trannon/Hanon, because/whichin one wave like a mountain at TheTeared[thebore]/hightide covers the litora/banks/shores/shoreline/bottom(,) and (it) ebbs/recedes like (every/allthe) other sea(s).” (- "Nennius".)
Trahannon seems to match one of 2 or 3 sites between Lemanis [Tribruit], and/or Anderida/Pevensey [Agned/Bregion], and/or Portchester / Southampton [ Badon].
Note the orthodox Trahannon candidate resorts to: "unlikely"; "seems odd"; "imagine"; "confused with"; "equally we may have completely the wrong river".
(i) river (&) name Trahannon match: Trahannon/Hanon name & river may match either the Arun/Tarrant (Arundel, near Chichester), or the Test/tese /terstan /ant/Anton(a)/antport/andover/hanton (Southampton / Winchester) (though scholars say this is a wrong etymology of Camden's)?
(ii) Teared/bore/wave covers, & ebbs like sea match: Perhaps compare that Chichester was Collingwood's "Tribruit" candidate, having tidal estuary attributes. "The shape of Southampton Water, which it [Test] enters, is suitable & the river must have been partly tidal (the fields above Testwood still flood at Spring tides)." (Evans.)
(iii) number/order match: [wonder number 2 may match battle number 12?] Fits with previous wonder #1 at Lemanis [Tribruit]; and next wonders #s 3 & 4 at Portchester / Southampton [Badon]? (The first 4 wonders all seem to go from Lemanis to Southampton?) The orthodox Trannon is hundreds of miles away from their Lomond.
The main candidates of others &/or ours for Trahannon include: Arun(del)/Tarrant (Street)/Tarente (Chichester, Sussex)? treyford (chichester)? Tarrant (Dorset)? Trent (Dorset Piddle)? Trent Brook (Dorset)? Trentan (Badsey Brook, Worcs)? Trannon (Leicestershire)? Trent/Traanta/T[a?]'ranta/Gabranto-/Tarranto-/[Trisanton]/Trentham (from hynt "path/way", and which is "famous for its spring tides/neaps and tidal bore/eagre", Staffordshire, Northern England)? the Trannon (Powys)? the Trisanna (Austria)? River Trisantonis/Trisanton[a] (Ptolemy 2ndC)? Tran(n)on/Tarannon/Trisanton[a] (ends the river Severn)? Moricambe/Morecambe Bay? Hod(d)nant (Llantwit, on the Severn)? Hodni stream/Nant Honddu/Hon-th-i (runs by Llanthony Priory / Priordy Llanddewi Nant Hodni)? river Hodni/Aberhodni (runs down to Brecknock / Brecon to join the Usk)? Havant? Hamo's port? Test / Anton(a)/Andover (Hants)? (Stour &) 'Salisbury Avon'? Trisanton(a(m))/Avon(am) (Tacitus, 109 ad)? Traeth Annwn "shore of the deep / region of the British Neptune"? Neptune (Lemanis)? aet thaere ruman e? Tidebrook? Thanet? Trahaiarn brother of Macsen? Trajectus/Bitton/Avon (Severn crossing?)?