Oceanography | Vol. 39, No. 1
8
et al., 2022; Lange et al., 2024; Anhaus et al., 2025). Its repeatable,
non-invasive capabilities make UHI especially suited for tracing
and quantifying fine-scale biogeochemical processes in remote
and sensitive environments.
UNDER-ICE MAPPING WITH HICYBOT
The HIcyBot system aims to produce co-georeferenced UHI and
three-dimensional (3D) structural data of the seafloor and overlying
fast ice based on several surveys conducted within hours of one
another (Figure 1). The optical components include three primary
subsystems: a central hyperspectral imager, a stereophotogrammet-
ric dual-camera system, and a USB live-stream reference camera
contained within a tethered underwater enclosure (Figure 2).
An eight-hydrophone-array ultra-short baseline (USBL) sen
sor was integrated to enable geolocation of pushbroom hyperspec-
tral frames with synchronized, timestamped Global Navigation
Satellite System (GNSS) and inertial navigation data. The
co-mounted dual-vision cameras leverage stereophotogramme-
try techniques to derive camera positions and orientations from
overlapping stereo images, providing independent vehicle pose
estimates that support local motion compensation for the UHI in
conditions where USBL signal quality is degraded beneath the ice
(Figure 2). The payload enclosure was incorporated into a custom
ized BlueROV2 heavy-configuration kit. A key design feature was
the addition of bottom ballast to create a pendulum-like configu
ration, enabling passive, stable vertical alignment for nadir-facing
(a) Sea-Ice Mode
(b) Seafloor Mode
FIGURE 1. HIcyBot is a proof-of-concept under-ice remotely operated vehicle (ROV) with hyperspectral imaging capability, designed for concomitant mapping
of (a) sympagic (ice-associated) habitats, and (b) benthic, seafloor-associated habitats that remain largely inaccessible to other marine sensing and survey
techniques. Pushbroom sensors record one spatial line per frame as the platform moves, forming a 3D hyperspectral cube (X, Y, λ) linking spatial and spec
tral domains. GNSS = Global Navigation Satellite System. USBL = ultra-short baseline. MPA = Marine Protected Area.